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From: Mathias Nyman <>
To: Vinod Koul <>
Cc: Christian Lamparter <>,
	Greg Kroah-Hartman <>,
	John Stultz <>,
	Mathias Nyman <>,,
	Bjorn Andersson <>,
	Yoshihiro Shimoda <>,
	USB list <>,
	Linux Kernel Mailing List <>,
	Alan Stern <>,
	Heikki Krogerus <>
Subject: Re: [PATCH v6 0/5] usb: xhci: Add support for Renesas USB controllers
Date: Tue, 4 Feb 2020 18:33:58 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <20200131084041.GI2841@vkoul-mobl>

On 31.1.2020 10.40, Vinod Koul wrote:
> Hi Mathias,
> On 30-01-20, 19:07, Mathias Nyman wrote:
>> On 25.1.2020 7.32, Vinod Koul wrote:
>>>>>>>> On Mon, Jan 13, 2020 at 12:42 AM Vinod Koul <> wrote:
>>>>>>>>> This series add support for Renesas USB controllers uPD720201 and uPD720202.
>>>>>>>>> These require firmware to be loaded and in case devices have ROM those can
>>>>>>>>> also be programmed if empty. If ROM is programmed, it runs from ROM as well.
>>>>>>>>> This includes two patches from Christian which supported these controllers
>>>>>>>>> w/o ROM and later my patches for ROM support and multiple firmware versions,
>>>>>>>>> debugfs hook for rom erase and export of xhci-pci functions.


>> There are a few other opens regarding this series. Mostly because I'm not (yet)
>> familiar with all the details, so I'll just just list them here.
>> - Is it really enough to add the Renesas driver to Makefile before xhci-pci
>>    driver to make sure it gets matched and probed based on vendor/device id
>>    before xhci-pci driver is matched and probed based on pci class?
>>    What if the Renesas driver is a module and xhci-pci compiled in?
> The driver loading rules are based on level and makefile order. So
> renesas will always be loaded before xhci driver. This is required since
> xhci claims all devices, so we need to make sure it loads before.
> I think we should make it inbuilt driver rather than a module. xhci
> driver is only inbuilt.
> If there is a better way to handle this, am all for it.
>> - Previously probe didn't return before hcd's were added and everything set up.
>>    Now with request_firmware_nowait() probe returns early successfully, and the
>>    old xhci_pci_probe() which sets up everything is called later by the request
>>    firmware callback. So there could be whole new set of races possible.
>>    For example pci remove can be called mid firmware loading, or when the old
>>    xhci_pci_probe is still setting up things.
> I think this is a valid concern. Let me think about how to solve this..
> maybe add a flag in remove which ensure remove doesnt run untill the
> probe/firmware callback is completed.

How about initiating async firmware loading before probe is called by using

Probe would then just check if there is a valid running firmware, if not just
defer probe until later (return -EPROBE_DEFER).

No need for a separate Renesas xhci driver, no worries about which driver
claims the device first, no races because of probe returning successfully
too early.

Can we check the device for a valid running firmware without disrupting a
ongoing firmware write?


  reply	other threads:[~2020-02-04 16:31 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-13  8:40 Vinod Koul
2020-01-13  8:40 ` [PATCH v6 1/5] usb: xhci: export few functions Vinod Koul
2020-01-13  8:40 ` [PATCH v6 2/5] usb: renesas-xhci: Add the renesas xhci driver Vinod Koul
2020-01-13  8:40 ` [PATCH v6 3/5] usb: renesas-xhci: Add ROM loader for uPD720201 Vinod Koul
2020-01-13  8:40 ` [PATCH v6 4/5] usb: renesas-xhci: allow multiple firmware versions Vinod Koul
2020-01-13  8:40 ` [PATCH v6 5/5] usb: xhci: provide a debugfs hook for erasing rom Vinod Koul
2020-01-13 20:09 ` [PATCH v6 0/5] usb: xhci: Add support for Renesas USB controllers John Stultz
2020-01-13 20:33   ` Christian Lamparter
2020-01-21  6:46     ` Vinod Koul
2020-01-21 20:26       ` Christian Lamparter
2020-01-24 21:38         ` Christian Lamparter
2020-01-25  5:32           ` Vinod Koul
2020-01-30 17:07             ` Mathias Nyman
2020-01-31  8:40               ` Vinod Koul
2020-02-04 16:33                 ` Mathias Nyman [this message]
2020-03-12  6:56                   ` Vinod Koul
2020-01-31 15:47               ` Alan Stern
2020-03-10 11:55                 ` Vinod Koul
2020-01-26  0:11 ` Andreas Böhler
2020-01-26 13:07   ` Christian Lamparter

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