Re: [PATCH] PCI: create revision file in sysfs

From	Emil Velikov <emil.l.velikov@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] PCI: create revision file in sysfs
Date	2016-11-08 12:30 +0100
Message-ID	<sBcLg-eL-9@gated-at.bofh.it> (permalink)
References	<syJu2-26a-3@gated-at.bofh.it> <syJu2-26a-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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[Dropping Jammy since his email bounces]

On 1 November 2016 at 15:47, Alex Deucher <alexdeucher@gmail.com> wrote:
> On Tue, Nov 1, 2016 at 11:42 AM, Emil Velikov <emil.l.velikov@gmail.com> wrote:
>> From: Emil Velikov <emil.velikov@collabora.com>
>>
>> Currently the revision isn't available via sysfs/libudev thus if one
>> wants to know the value they need to read through the config file.
>>
>> This in itself wakes/powers up the device, causing unwanted delay
>> since it can be quite costly.
>>
>> Expose the revision as a separate file, just like we do for the device,
>> vendor, their subsystem version and class.
>>
>> Cc: Jammy Zhou <Jammy.Zhou@amd.com>
>> Cc: Michel Dänzer <michel.daenzer@amd.com>
>> Cc: Bjorn Helgaas <bhelgaas@google.com>
>> Cc: linux-pci@vger.kernel.org
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
>
> Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
>
Thanks Alex.

Gents, to elaborate a bit:

When using the Mesa drivers alongside firefox [1] (since Mesa 13.0),
glxinfo (Mesa 10.0) and others, all the GPUs* will be awaken, causing
unwanted delays and increased power usage.
From the userspace POV we have two distinct users who require the
revision file - libdrm and libpciaccess. * The latter would even wake
up _all_ the devices located on a PCI bus !

Let me know if you'd like the above in the patch summary, meanwhile
I'll poke and collect a few more ack/r-b/t-b.

Thanks
Emil

[1] https://bugs.freedesktop.org/show_bug.cgi?id=98502

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Re: [PATCH] PCI: create revision file in sysfs Alex Deucher <alexdeucher@gmail.com> - 2016-11-01 16:50 +0100
  Re: [PATCH] PCI: create revision file in sysfs Emil Velikov <emil.l.velikov@gmail.com> - 2016-11-08 12:30 +0100

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