2016-11-01 15:42:44

by Emil Velikov

[permalink] [raw]
Subject: [PATCH] PCI: create revision file in sysfs

From: Emil Velikov <[email protected]>

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 <[email protected]>
Cc: Michel Dänzer <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Emil Velikov <[email protected]>
---
Gents, I'm not subscribed to the mailing list so please keep me in the
CC chain.

Thanks
Emil
---
drivers/pci/pci-sysfs.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index bcd10c7..0666287 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -50,6 +50,7 @@ pci_config_attr(vendor, "0x%04x\n");
pci_config_attr(device, "0x%04x\n");
pci_config_attr(subsystem_vendor, "0x%04x\n");
pci_config_attr(subsystem_device, "0x%04x\n");
+pci_config_attr(revision, "0x%02x\n");
pci_config_attr(class, "0x%06x\n");
pci_config_attr(irq, "%u\n");

@@ -568,6 +569,7 @@ static struct attribute *pci_dev_attrs[] = {
&dev_attr_device.attr,
&dev_attr_subsystem_vendor.attr,
&dev_attr_subsystem_device.attr,
+ &dev_attr_revision.attr,
&dev_attr_class.attr,
&dev_attr_irq.attr,
&dev_attr_local_cpus.attr,
--
2.9.3


2016-11-01 15:47:43

by Alex Deucher

[permalink] [raw]
Subject: Re: [PATCH] PCI: create revision file in sysfs

On Tue, Nov 1, 2016 at 11:42 AM, Emil Velikov <[email protected]> wrote:
> From: Emil Velikov <[email protected]>
>
> 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 <[email protected]>
> Cc: Michel Dänzer <[email protected]>
> Cc: Bjorn Helgaas <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Emil Velikov <[email protected]>

Reviewed-by: Alex Deucher <[email protected]>

> ---
> Gents, I'm not subscribed to the mailing list so please keep me in the
> CC chain.
>
> Thanks
> Emil
> ---
> drivers/pci/pci-sysfs.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index bcd10c7..0666287 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -50,6 +50,7 @@ pci_config_attr(vendor, "0x%04x\n");
> pci_config_attr(device, "0x%04x\n");
> pci_config_attr(subsystem_vendor, "0x%04x\n");
> pci_config_attr(subsystem_device, "0x%04x\n");
> +pci_config_attr(revision, "0x%02x\n");
> pci_config_attr(class, "0x%06x\n");
> pci_config_attr(irq, "%u\n");
>
> @@ -568,6 +569,7 @@ static struct attribute *pci_dev_attrs[] = {
> &dev_attr_device.attr,
> &dev_attr_subsystem_vendor.attr,
> &dev_attr_subsystem_device.attr,
> + &dev_attr_revision.attr,
> &dev_attr_class.attr,
> &dev_attr_irq.attr,
> &dev_attr_local_cpus.attr,
> --
> 2.9.3
>
> _______________________________________________
> dri-devel mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

2016-11-08 11:27:56

by Emil Velikov

[permalink] [raw]
Subject: Re: [PATCH] PCI: create revision file in sysfs

[Dropping Jammy since his email bounces]

On 1 November 2016 at 15:47, Alex Deucher <[email protected]> wrote:
> On Tue, Nov 1, 2016 at 11:42 AM, Emil Velikov <[email protected]> wrote:
>> From: Emil Velikov <[email protected]>
>>
>> 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 <[email protected]>
>> Cc: Michel Dänzer <[email protected]>
>> Cc: Bjorn Helgaas <[email protected]>
>> Cc: [email protected]
>> Cc: [email protected]
>> Signed-off-by: Emil Velikov <[email protected]>
>
> Reviewed-by: Alex Deucher <[email protected]>
>
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