[PATCH] drm/amdgpu: Add sysfs file for VBIOS

Russell, Kent Kent.Russell at amd.com
Thu Aug 24 21:30:12 UTC 2017


The plan is for the vbios version to be available through the ROCM-SMI utility. We have the GPU power usage listed in the debugfs currently. If they are both to be used for a userspace utility, should we be moving both of those to sysfs instead?

Kent

KENT RUSSELL
Software Engineer | Vertical Workstation/Compute
1 Commerce Valley Drive East
Markham, ON L3T 7X6
Canada
O +(1) 289-695-2122   | Ext x72122


________________________________
From: Christian König <deathsimple at vodafone.de>
Sent: Thursday, August 24, 2017 2:10:35 PM
To: Russell, Kent; Alex Deucher; Kuehling, Felix
Cc: amd-gfx at lists.freedesktop.org
Subject: Re: [PATCH] drm/amdgpu: Add sysfs file for VBIOS

Actually the main difference is not root vs. user, but rather unstable
vs stable interface.

If you want a stable interface for an userspace tool you should use
sysfs, if you don't care about that you should use debugfs.

Christian.

Am 24.08.2017 um 18:37 schrieb Russell, Kent:
> We already access the GPU Power usage via debugfs, which is why I didn't think it was a huge deal to switch it over, since we already need root access for the SMI due to that.
>
>   Kent
>
> -----Original Message-----
> From: Alex Deucher [mailto:alexdeucher at gmail.com]
> Sent: Thursday, August 24, 2017 11:39 AM
> To: Kuehling, Felix
> Cc: Russell, Kent; Christian König; amd-gfx at lists.freedesktop.org
> Subject: Re: [PATCH] drm/amdgpu: Add sysfs file for VBIOS
>
> On Thu, Aug 24, 2017 at 11:35 AM, Kuehling, Felix <Felix.Kuehling at amd.com> wrote:
>> Debugfs is only accessible by Root. The BIOS version is already reported in the kernel log, which is visible to everyone. So why hide this away in debugfs?
>>
>> I think Kent's intention is to add VBIOS version reporting to the rocm-smi tool. I'd prefer using a stable interface like sysfs, and one that doesn't require root access in a tool like rocm-smi.
>>
> Ah, ok, sysfs is fine in that case.  I thought this was just general debugging stuff.
>
> Alex
>
>> Regards,
>>    Felix
>> ________________________________________
>> From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> on behalf of
>> Russell, Kent <Kent.Russell at amd.com>
>> Sent: Thursday, August 24, 2017 9:06:22 AM
>> To: Alex Deucher
>> Cc: Christian König; amd-gfx at lists.freedesktop.org
>> Subject: RE: [PATCH] drm/amdgpu: Add sysfs file for VBIOS
>>
>> I can definitely add that as well.
>>
>>   Kent
>>
>> -----Original Message-----
>> From: Alex Deucher [mailto:alexdeucher at gmail.com]
>> Sent: Thursday, August 24, 2017 8:56 AM
>> To: Russell, Kent
>> Cc: Christian König; amd-gfx at lists.freedesktop.org
>> Subject: Re: [PATCH] drm/amdgpu: Add sysfs file for VBIOS
>>
>> On Thu, Aug 24, 2017 at 5:58 AM, Russell, Kent <Kent.Russell at amd.com> wrote:
>>> No real reason for sysfs instead of debugfs, I just picked the one that was more familiar with. I can definitely move it to debugfs instead. I will also clean up the commit message per Michel's comments. Thank you!
>>>
>> While you are at it, can you expose the vbios binary itself via debugfs?  That's been on by todo list for a while.
>>
>> Alex
>>
>>>   Kent
>>>
>>> -----Original Message-----
>>> From: Christian König [mailto:deathsimple at vodafone.de]
>>> Sent: Thursday, August 24, 2017 2:22 AM
>>> To: Russell, Kent; amd-gfx at lists.freedesktop.org
>>> Subject: Re: [PATCH] drm/amdgpu: Add sysfs file for VBIOS
>>>
>>> Am 23.08.2017 um 20:12 schrieb Kent Russell:
>>>> This won't change after initialization, so we can add the
>>>> information when we parse the atombios information. This ensures
>>>> that we can find out the VBIOS, even when the dmesg buffer fills up,
>>>> and makes it easier to associate which VBIOS is for which GPU on
>>>> mGPU configurations. Set the size to 20 characters in case of some
>>>> weird VBIOS suffix that exceeds the expected 17 character format
>>>> (3-8-3\0)
>>> Is there any reason that needs to be sysfs? Sounds more like an use case for debugfs.
>>>
>>> Christian.
>>>
>>>> Signed-off-by: Kent Russell <kent.russell at amd.com>
>>>> ---
>>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 23 +++++++++++++++++++++++
>>>>    drivers/gpu/drm/amd/amdgpu/atom.c          |  5 ++++-
>>>>    drivers/gpu/drm/amd/amdgpu/atom.h          |  1 +
>>>>    3 files changed, 28 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>> index a1f9424..f40be71 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>> @@ -888,6 +888,20 @@ static uint32_t cail_ioreg_read(struct card_info *info, uint32_t reg)
>>>>        return r;
>>>>    }
>>>>
>>>> +static ssize_t amdgpu_atombios_get_vbios_version(struct device *dev,
>>>> +                                              struct device_attribute *attr,
>>>> +                                              char *buf) {
>>>> +     struct drm_device *ddev = dev_get_drvdata(dev);
>>>> +     struct amdgpu_device *adev = ddev->dev_private;
>>>> +     struct atom_context *ctx = adev->mode_info.atom_context;
>>>> +
>>>> +     return snprintf(buf, PAGE_SIZE, "%s\n", ctx->vbios_version); }
>>>> +
>>>> +static DEVICE_ATTR(vbios_version, 0444, amdgpu_atombios_get_vbios_version,
>>>> +                NULL);
>>>> +
>>>>    /**
>>>>     * amdgpu_atombios_fini - free the driver info and callbacks for atombios
>>>>     *
>>>> @@ -907,6 +921,7 @@ static void amdgpu_atombios_fini(struct amdgpu_device *adev)
>>>>        adev->mode_info.atom_context = NULL;
>>>>        kfree(adev->mode_info.atom_card_info);
>>>>        adev->mode_info.atom_card_info = NULL;
>>>> +     device_remove_file(adev->dev, &dev_attr_vbios_version);
>>>>    }
>>>>
>>>>    /**
>>>> @@ -923,6 +938,7 @@ static int amdgpu_atombios_init(struct amdgpu_device *adev)
>>>>    {
>>>>        struct card_info *atom_card_info =
>>>>            kzalloc(sizeof(struct card_info), GFP_KERNEL);
>>>> +     int ret;
>>>>
>>>>        if (!atom_card_info)
>>>>                return -ENOMEM;
>>>> @@ -959,6 +975,13 @@ static int amdgpu_atombios_init(struct amdgpu_device *adev)
>>>>                amdgpu_atombios_scratch_regs_init(adev);
>>>>                amdgpu_atombios_allocate_fb_scratch(adev);
>>>>        }
>>>> +
>>>> +     ret = device_create_file(adev->dev, &dev_attr_vbios_version);
>>>> +     if (ret) {
>>>> +             DRM_ERROR("Failed to create device file for VBIOS version\n");
>>>> +             return ret;
>>>> +     }
>>>> +
>>>>        return 0;
>>>>    }
>>>>
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/atom.c
>>>> b/drivers/gpu/drm/amd/amdgpu/atom.c
>>>> index d69aa2e..69500a8 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/atom.c
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/atom.c
>>>> @@ -1343,8 +1343,11 @@ struct atom_context *amdgpu_atom_parse(struct card_info *card, void *bios)
>>>>                idx = 0x80;
>>>>
>>>>        str = CSTR(idx);
>>>> -     if (*str != '\0')
>>>> +     if (*str != '\0') {
>>>>                pr_info("ATOM BIOS: %s\n", str);
>>>> +             strlcpy(ctx->vbios_version, str, sizeof(ctx->vbios_version));
>>>> +     }
>>>> +
>>>>
>>>>        return ctx;
>>>>    }
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/atom.h
>>>> b/drivers/gpu/drm/amd/amdgpu/atom.h
>>>> index ddd8045..a391709 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/atom.h
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/atom.h
>>>> @@ -140,6 +140,7 @@ struct atom_context {
>>>>        int io_mode;
>>>>        uint32_t *scratch;
>>>>        int scratch_size_bytes;
>>>> +     char vbios_version[20];
>>>>    };
>>>>
>>>>    extern int amdgpu_atom_debug;
>>>
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