Re: [PATCH 14/15] ide: rework the code for selecting the best DMA transfer mode

[Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>]

Hi,

Sergei Shtylyov wrote:
> 
> Hello.
> 
> Bartlomiej Zolnierkiewicz wrote:
> 
>> [PATCH] ide: rework the code for selecting the best DMA transfer mode
> 
>    Here's another portion of comments...
> 
>> Depends on the "ide: fix UDMA/MWDMA/SWDMA masks" patch.
> 
>> * add ide_hwif_t.filter_udma_mask hook for filtering UDMA mask
> 
>    Erm, maybe a shorter method name like udma_filter would go with the others
> better.  But well, that's my taste. :-)

done

>>   (use it in alim15x3, hpt366, siimage and serverworks drivers)
>> * add ide_max_dma_mode() for finding best DMA mode for the device
>>   (loosely based on some older libata-core.c code)
>> * convert ide_dma_speed() users to use ide_max_dma_mode()
>> * make ide_rate_filter() take "ide_drive_t *drive" as an argument instead
>>   of "u8 mode" and teach it to how to use UDMA mask to do filtering
>> * use ide_rate_filter() in hpt366 driver
>> * remove no longer needed ide_dma_speed() and *_ratemask()
>> * unexport eighty_ninty_three()
> 
>> Index: b/drivers/ide/ide-dma.c
>> ===================================================================
>> --- a/drivers/ide/ide-dma.c
>> +++ b/drivers/ide/ide-dma.c
>> @@ -705,6 +705,80 @@ int ide_use_dma(ide_drive_t *drive)
>>
>>  EXPORT_SYMBOL_GPL(ide_use_dma);
>>
>> +static const u8 xfer_mode_bases[] = {
>> +     XFER_UDMA_0,
>> +     XFER_MW_DMA_0,
>> +     XFER_SW_DMA_0,
>> +};
>> +
>> +static unsigned int ide_get_mode_mask(ide_drive_t *drive, u8 base)
>> +{
>> +     struct hd_driveid *id = drive->id;
>> +     ide_hwif_t *hwif = drive->hwif;
>> +     unsigned int mask = 0;
>> +
>> +     switch(base) {
>> +     case XFER_UDMA_0:
>> +             if ((id->field_valid & 4) == 0)
>> +                     break;
>> +
>> +             mask = id->dma_ultra & hwif->ultra_mask;
>> +
>> +             if (hwif->filter_udma_mask)
>> +                     mask &= hwif->filter_udma_mask(drive);
>> +
>> +             if ((mask & 0x78) && (eighty_ninty_three(drive) == 0))
>> +                     mask &= 0x07;
>> +             break;
>> +     case XFER_MW_DMA_0:
>> +             mask = id->dma_mword & hwif->mwdma_mask;
>> +             break;
>> +     case XFER_SW_DMA_0:
>> +             mask = id->dma_1word & hwif->swdma_mask;
>> +             break;
>> +     default:
>> +             BUG();
>> +             break;
>> +     }
>> +
>> +     return mask;
>> +}
>> +
>> +/**
>> + *   ide_max_dma_mode        -       compute DMA speed
>> + *   @drive: IDE device
>> + *
>> + *   Checks the drive capabilities and returns the speed to use
>> + *   for the DMA transfer.  Returns 0 if the drive is incapable
>> + *   of DMA transfers.
>> + */
>> +
>> +u8 ide_max_dma_mode(ide_drive_t *drive)
>> +{
>> +     ide_hwif_t *hwif = drive->hwif;
>> +     unsigned int mask;
>> +     int x, i;
>> +     u8 mode = 0;
>> +
>> +     if (drive->media != ide_disk && hwif->atapi_dma == 0)
>> +             return 0;
>> +
>> +     for (i = 0; i < ARRAY_SIZE(xfer_mode_bases); i++) {
>> +             mask = ide_get_mode_mask(drive, xfer_mode_bases[i]);
>> +             x = fls(mask) - 1;
>> +             if (x >= 0) {
>> +                     mode = xfer_mode_bases[i] + x;
>> +                     break;
>> +             }
>> +     }
>> +
>> +     printk(KERN_DEBUG "%s: selected mode 0x%x\n", drive->name, mode);
>> +
>> +     return mode;
>> +}
>> +
>> +EXPORT_SYMBOL_GPL(ide_max_dma_mode);
>> +
> 
>    I didn't quite like the array/loop approach but well, that's my taste (I'd
> rather put the mode-from-mask evaluation to the function and call it thrice)...

The mode-from-mask approach is indeed nicer.  If you send me a patch to
use the mode-from-mask evaluation I'll happily apply it. :)

However the array/loop approach is also definitively an improvement
over the current code.

>> Index: b/drivers/ide/ide-lib.c
>> ===================================================================
>> --- a/drivers/ide/ide-lib.c
>> +++ b/drivers/ide/ide-lib.c
>> @@ -69,123 +69,34 @@ char *ide_xfer_verbose (u8 xfer_rate)
>>  EXPORT_SYMBOL(ide_xfer_verbose);
>>
>>  /**
>> - *   ide_dma_speed   -       compute DMA speed
>> - *   @drive: drive
>> - *   @mode:  modes available
>> - *
>> - *   Checks the drive capabilities and returns the speed to use
>> - *   for the DMA transfer.  Returns 0 if the drive is incapable
>> - *   of DMA transfers.
>> - */
>> -
>> -u8 ide_dma_speed(ide_drive_t *drive, u8 mode)
> 
> [...]
> 
>> -EXPORT_SYMBOL(ide_dma_speed);
> 
>    Alas, my ide_dma_speed() fix is going to be oudated rather quickly... :-)

C'est la vie :)

>> Index: b/drivers/ide/pci/hpt366.c
>> ===================================================================
>> --- a/drivers/ide/pci/hpt366.c
>> +++ b/drivers/ide/pci/hpt366.c
>> @@ -513,43 +513,31 @@ static int check_in_drive_list(ide_drive
>>       return 0;
>>  }
>>
>> -static u8 hpt3xx_ratemask(ide_drive_t *drive)
>> -{
>> -     struct hpt_info *info   = pci_get_drvdata(HWIF(drive)->pci_dev);
>> -     u8 mode                 = info->max_mode;
>> -
>> -     if (!eighty_ninty_three(drive) && mode)
>> -             mode = min(mode, (u8)1);
>> -     return mode;
>> -}
>> -
>>  /*
>>   *   Note for the future; the SATA hpt37x we must set
>>   *   either PIO or UDMA modes 0,4,5
>>   */
>> -
>> -static u8 hpt3xx_ratefilter(ide_drive_t *drive, u8 speed)
>> +
>> +static u8 hpt3xx_filter_udma_mask(ide_drive_t *drive)
>>  {
>>       struct hpt_info *info   = pci_get_drvdata(HWIF(drive)->pci_dev);
>>       u8 chip_type            = info->chip_type;
>> -     u8 mode                 = hpt3xx_ratemask(drive);
>> -
>> -     if (drive->media != ide_disk)
>> -             return min(speed, (u8)XFER_PIO_4);
>> +     u8 mode                 = info->max_mode;
>> +     u8 mask;
>>
>>       switch (mode) {
>>               case 0x04:
>> -                     speed = min_t(u8, speed, XFER_UDMA_6);
>> +                     mask = 0x7f;
>>                       break;
>>               case 0x03:
>> -                     speed = min_t(u8, speed, XFER_UDMA_5);
>> +                     mask = 0x3f;
>>                       if (chip_type >= HPT374)
>>                               break;
>>                       if (!check_in_drive_list(drive, bad_ata100_5))
>>                               goto check_bad_ata33;
>>                       /* fall thru */
>>               case 0x02:
>> -                     speed = min_t(u8, speed, XFER_UDMA_4);
>> +                     mask = 0x1f;
>>
>>                       /*
>>                        * CHECK ME, Does this need to be changed to HPT374 ??
>> @@ -560,13 +548,13 @@ static u8 hpt3xx_ratefilter(ide_drive_t
>>                           !check_in_drive_list(drive, bad_ata66_4))
>>                               goto check_bad_ata33;
>>
>> -                     speed = min_t(u8, speed, XFER_UDMA_3);
>> +                     mask = 0x0f;
>>                       if (HPT366_ALLOW_ATA66_3 &&
>>                           !check_in_drive_list(drive, bad_ata66_3))
>>                               goto check_bad_ata33;
>>                       /* fall thru */
>>               case 0x01:
>> -                     speed = min_t(u8, speed, XFER_UDMA_2);
>> +                     mask = 0x07;
>>
>>               check_bad_ata33:
>>                       if (chip_type >= HPT370A)
>> @@ -576,10 +564,10 @@ static u8 hpt3xx_ratefilter(ide_drive_t
>>                       /* fall thru */
>>               case 0x00:
>>               default:
>> -                     speed = min_t(u8, speed, XFER_MW_DMA_2);
>> +                     mask = 0x00;
>>                       break;
>>       }
>> -     return speed;
>> +     return mask;
>>  }
> 
>    Erm, I see.  This driver will need some redesign because 'struct hpt_info'
> was fitted for the old rate filtering model.  Looks like the 'max_mode' field
> should be replaced by 'ultra_mask' there...

yes...

>>  static u32 get_speed_setting(u8 speed, struct hpt_info *info)
>> @@ -607,12 +595,19 @@ static int hpt36x_tune_chipset(ide_drive
>>       ide_hwif_t *hwif        = HWIF(drive);
>>       struct pci_dev  *dev    = hwif->pci_dev;
>>       struct hpt_info *info   = pci_get_drvdata(dev);
>> -     u8  speed               = hpt3xx_ratefilter(drive, xferspeed);
>> +     u8  speed               = ide_rate_filter(drive, xferspeed);
>>       u8  itr_addr            = drive->dn ? 0x44 : 0x40;
>> -     u32 itr_mask            = speed < XFER_MW_DMA_0 ? 0x30070000 :
>> -                              (speed < XFER_UDMA_0   ? 0xc0070000 : 0xc03800ff);
>> -     u32 new_itr             = get_speed_setting(speed, info);
>>       u32 old_itr             = 0;
>> +     u32 itr_mask, new_itr;
>> +
>> +     /* TODO: move this to ide_rate_filter() [ check ->atapi_dma ] */
>> +     if (drive->media != ide_disk)
>> +             speed = min_t(u8, speed, XFER_PIO_4);
>> +
> 
>    When I think about it, it seems quite stupid to set a PIO mode instead of
> a requested DMA one.  So, this is actually a questionable piece of code in
> this driver...

This can safely vanish when core code gets fixed to correctly check device+host
supported PIO/DMA modes before calling ->tuneproc/->speedproc for user space
originated code change requests.

As for now IMHO it is the best to just leave it alone...

>    Well, I must note the sorrow fact that both the IDE susbsytem as a whole
> doesn't keep track of PIO/DMA modes separately (having only current_mode) and
> the many drivers also fail to handle the timing registers shared by PIO/DMA
> modes correctly (well, it's actually also a hardware design issue :-).

Actually, I have an unfinished patch to fix it but it depends on
many other unfinished patches... *sigh*...

>> +     itr_mask = speed < XFER_MW_DMA_0 ? 0x30070000 :
>> +               (speed < XFER_UDMA_0   ? 0xc0070000 : 0xc03800ff);
>> +
>> +     new_itr = get_speed_setting(speed, info);
> 
>    Well, I liked this code where it was. But anyway, it's going to be
> replaced RSN...
> 
>> @@ -632,12 +627,19 @@ static int hpt37x_tune_chipset(ide_drive
>>       ide_hwif_t *hwif        = HWIF(drive);
>>       struct pci_dev  *dev    = hwif->pci_dev;
>>       struct hpt_info *info   = pci_get_drvdata(dev);
>> -     u8  speed               = hpt3xx_ratefilter(drive, xferspeed);
>> +     u8  speed               = ide_rate_filter(drive, xferspeed);
>>       u8  itr_addr            = 0x40 + (drive->dn * 4);
>> -     u32 itr_mask            = speed < XFER_MW_DMA_0 ? 0x303c0000 :
>> -                              (speed < XFER_UDMA_0   ? 0xc03c0000 : 0xc1c001ff);
>> -     u32 new_itr             = get_speed_setting(speed, info);
>>       u32 old_itr             = 0;
>> +     u32 itr_mask, new_itr;
>> +
>> +     /* TODO: move this to ide_rate_filter() [ check ->atapi_dma ] */
>> +     if (drive->media != ide_disk)
>> +             speed = min_t(u8, speed, XFER_PIO_4);
>> +
>> +     itr_mask = speed < XFER_MW_DMA_0 ? 0x303c0000 :
>> +               (speed < XFER_UDMA_0   ? 0xc03c0000 : 0xc1c001ff);
>> +
>> +     new_itr = get_speed_setting(speed, info);
> 
>    Same comments here...
> 
>> Index: b/drivers/ide/pci/serverworks.c
>> ===================================================================
>> --- a/drivers/ide/pci/serverworks.c
>> +++ b/drivers/ide/pci/serverworks.c
>> @@ -65,16 +65,16 @@ static int check_in_drive_lists (ide_dri
>>       return 0;
>>  }
>>
>> -static u8 svwks_ratemask (ide_drive_t *drive)
>> +static u8 svwks_filter_udma_mask(ide_drive_t *drive)
>>  {
>>       struct pci_dev *dev     = HWIF(drive)->pci_dev;
>> -     u8 mode = 0;
>> +     u8 mask = 0;
> 
>    Hm, this looks like it needs rework...

...some time later. 8)

>>       if (!svwks_revision)
>>               pci_read_config_byte(dev, PCI_REVISION_ID, &svwks_revision);
>>
>>       if (dev->device == PCI_DEVICE_ID_SERVERWORKS_HT1000IDE)
>> -             return 2;
>> +             return 0x1f;
>>       if (dev->device == PCI_DEVICE_ID_SERVERWORKS_OSB4IDE) {
>>               u32 reg = 0;
>>               if (isa_dev)
>> @@ -86,25 +86,31 @@ static u8 svwks_ratemask (ide_drive_t *d
>>               if(drive->media == ide_disk)
>>                       return 0;
>>               /* Check the OSB4 DMA33 enable bit */
>> -             return ((reg & 0x00004000) == 0x00004000) ? 1 : 0;
>> +             return ((reg & 0x00004000) == 0x00004000) ? 0x07 : 0;
>>       } else if (svwks_revision < SVWKS_CSB5_REVISION_NEW) {
>> -             return 1;
>> +             return 0x07;
>>       } else if (svwks_revision >= SVWKS_CSB5_REVISION_NEW) {
>> -             u8 btr = 0;
>> +             u8 btr = 0, mode;
>>               pci_read_config_byte(dev, 0x5A, &btr);
>>               mode = btr & 0x3;
>> -             if (!eighty_ninty_three(drive))
>> -                     mode = min(mode, (u8)1);
>> +
>>               /* If someone decides to do UDMA133 on CSB5 the same
>>                  issue will bite so be inclusive */
>>               if (mode > 2 && check_in_drive_lists(drive, svwks_bad_ata100))
>>                       mode = 2;
>> +
>> +             switch(mode) {
>> +             case 2:  mask = 0x1f; break;
>> +             case 1:  mask = 0x07; break;
>> +             default: mask = 0x00; break;
>> +             }
>>       }
>>       if (((dev->device == PCI_DEVICE_ID_SERVERWORKS_CSB6IDE) ||
>>            (dev->device == PCI_DEVICE_ID_SERVERWORKS_CSB6IDE2)) &&
>>           (!(PCI_FUNC(dev->devfn) & 1)))
>> -             mode = 2;
>> -     return mode;
>> +             mask = 0x1f;
>> +
>> +     return mask;
>>  }
> 
>    Hm, what was the problem with setting the proper masks based on PCI
> device ID in the init. code?
> That'd have greatly simplified the filter...

I don't see a problem with doing it during initialization but simplifying
this code wasn't the goal of this patch and can be done in the future.

>> Index: b/drivers/ide/pci/siimage.c
>> ===================================================================
>> --- a/drivers/ide/pci/siimage.c
>> +++ b/drivers/ide/pci/siimage.c
>> @@ -116,45 +116,41 @@ static inline unsigned long siimage_seld
>>  }
>>
>>  /**
>> - *   siimage_ratemask        -       Compute available modes
>> - *   @drive: IDE drive
>> + *   sil_filter_udma_mask    -       compute UDMA mask
>> + *   @drive: IDE device
>> + *
>> + *   Compute the available UDMA speeds for the device on the interface.
>>   *
>> - *   Compute the available speeds for the devices on the interface.
>>   *   For the CMD680 this depends on the clocking mode (scsc), for the
>> - *   SI3312 SATA controller life is a bit simpler. Enforce UDMA33
>> - *   as a limit if there is no 80pin cable present.
>> + *   SI3112 SATA controller life is a bit simpler.
>>   */
>> -
>> -static byte siimage_ratemask (ide_drive_t *drive)
>> +
>> +static u8 sil_filter_udma_mask(ide_drive_t *drive)
>>  {
>> -     ide_hwif_t *hwif        = HWIF(drive);
>> -     u8 mode = 0, scsc = 0;
>> +     ide_hwif_t *hwif = drive->hwif;
>>       unsigned long base = (unsigned long) hwif->hwif_data;
>> +     u8 mask = 0, scsc = 0;
>>
>>       if (hwif->mmio)
>>               scsc = hwif->INB(base + 0x4A);
>>       else
>>               pci_read_config_byte(hwif->pci_dev, 0x8A, &scsc);
>>
>> -     if(is_sata(hwif))
>> -     {
>> -             if(strstr(drive->id->model, "Maxtor"))
>> -                     return 3;
>> -             return 4;
>> +     if (is_sata(hwif)) {
>> +             mask = strstr(drive->id->model, "Maxtor") ? 0x3f : 0x7f;
>> +             goto out;
>>       }
>> -
>> +
>>       if ((scsc & 0x30) == 0x10)      /* 133 */
>> -             mode = 4;
>> +             mask = 0x7f;
>>       else if ((scsc & 0x30) == 0x20) /* 2xPCI */
>> -             mode = 4;
>> +             mask = 0x7f;
>>       else if ((scsc & 0x30) == 0x00) /* 100 */
>> -             mode = 3;
>> +             mask = 0x3f;
>>       else    /* Disabled ? */
>>               BUG();
> 
>    Most probably this is doable at init. time also...

ditto

patches welcomed (I added this to the IDE tree TODO)

> MBR, Sergei
> 
> PS: I understand that the intent wasn not to make this rewrite optimal but
> do it quick and with least affect.  And I certainly may handle hpt366.c
> redesign... :-)

Please do.

Thanks,
Bart