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From: Michael Schmitz <schmitzmic@gmail.com>
To: Finn Thain <fthain@telegraphics.com.au>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
	"David S. Miller" <davem@davemloft.net>,
	linux-m68k <linux-m68k@vger.kernel.org>,
	netdev <netdev@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH net] macmace: Set platform device coherent_dma_mask
Date: Fri, 11 May 2018 16:18:01 +1200	[thread overview]
Message-ID: <0b13a08d-ba2d-b9dc-4fd9-1f6bad5cd1ee@gmail.com> (raw)
In-Reply-To: <alpine.LNX.2.21.1805111221180.8@nippy.intranet>

Hi Finn,

Am 11.05.2018 um 15:28 schrieb Finn Thain:
> On Fri, 11 May 2018, Michael Schmitz wrote:
> 
>>>> Which begs the question: why can' you set up all Nubus bus devices' 
>>>> DMA masks in nubus_device_register(), or nubus_add_board()?
>>>
>>> I am expecting to see the same WARNING from the nubus sonic driver but 
>>> it hasn't happened yet, so I don't have a patch for it yet. In 
>>> anycase, the nubus fix would be a lot like the zorro bus fix, so I 
>>> don't see a problem.
>>
>> That's odd. But what I meant to say is that by setting up 
>> dma_coherent_mask in nubus_add_board(), and pointing dma_mask to that, 
>> ypu won't need any patches to Nubus device drivers.
> 
> Right. I think I've already acknowledged that. But it's off-topic, because 
> the patches under review are for platform drivers. Those patches fix an 
> actual bug that I've observed. Whereas, the nubus driver dma mask issue 
> that you raised is purely theoretical at this stage.

I had lost track of the fact that macsonic can be probed as either Nubus
or platform device. Sorry for the noise.

I'm afraid using platform_device_register() (which you already use for
the SCC devices) is the only option handling this on a per-device basis
without touching platform core code, while at the same time keeping the
DMA mask setup out of device drivers (I can see Geert's point there -
device driver code might be shared across implementations of the device
on platforms with different DMA mask requirements,, something the driver
can't be expected to know about).

Cheers,

	Michael

  reply	other threads:[~2018-05-11  4:18 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <S1751632AbeECEYA/20180503042400Z+254@vger.kernel.org>
2018-05-03  7:25 ` Geert Uytterhoeven
2018-05-03  8:38   ` Finn Thain
2018-05-03  8:46     ` Geert Uytterhoeven
2018-05-03  8:51       ` Christoph Hellwig
2018-05-03 20:24         ` Michael Schmitz
2018-05-04  7:24           ` Geert Uytterhoeven
2018-05-04  8:16             ` Michael Schmitz
2018-05-10  1:25         ` Finn Thain
2018-05-10  1:25       ` Finn Thain
2018-05-10 20:27         ` Michael Schmitz
2018-05-10 23:55           ` Finn Thain
2018-05-11  2:11             ` Michael Schmitz
2018-05-11  3:28               ` Finn Thain
2018-05-11  4:18                 ` Michael Schmitz [this message]
2018-05-11  5:28                   ` Finn Thain
2018-05-11  9:30                     ` Michael Schmitz
2018-05-11 10:06                       ` Finn Thain
2018-05-11 22:02                         ` Michael Schmitz
2018-05-03  4:23 Finn Thain

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