Às 13:42 de 14/07/22, Alex Deucher escreveu:
> On Wed, Jul 13, 2022 at 11:15 AM André Almeida <andrealmeid@xxxxxxxxxx> wrote:
>>
>> GFXOFF has two different "state" values: one to define if the GPU is
>> allowed/disallowed to enter GFXOFF, usually called state; and another
>> one to define if currently GFXOFF is being used, usually called status.
>> Even when GFXOFF is allowed, GPU firmware can decide to not used it
>> accordingly to the GPU load.
>>
>> Userspace can allow/disallow GPUs to enter into GFXOFF via debugfs. The
>> kernel maintains a counter of requests for GFXOFF (gfx_off_req_count)
>> that should be decreased to allow GFXOFF and increased to disallow.
>>
>> The issue with this interface is that userspace can't be sure if GFXOFF
>> is currently allowed. Even by checking amdgpu_gfxoff file, one might get
>> an ambiguous 2, that means that GPU is currently out of GFXOFF, but that
>> can be either because it's currently disallowed or because it's allowed
>> but given the current GPU load it's enabled. Then, userspace needs to
>> rely on the fact that GFXOFF is enabled by default on boot and to track
>> this information.
>>
>> To make userspace life easier and GFXOFF more reliable, return the
>> current state of GFXOFF to userspace when reading amdgpu_gfxoff with the
>> same semantics of writing: 0 means not allowed, not 0 means allowed.
>>
>
> This looks good. Can you document this in the amdgpu kerneldoc?
>
Sure, let me send a v2 with that
> Alex
>
>> Expose the current status of GFXOFF through a new file,
>> amdgpu_gfxoff_status.
>>
>> Signed-off-by: André Almeida <andrealmeid@xxxxxxxxxx>
>> ---
>> drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 49 ++++++++++++++++++++-
>> 1 file changed, 47 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>> index f3b3c688e4e7..e2eec985adb3 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>> @@ -1117,13 +1117,50 @@ static ssize_t amdgpu_debugfs_gfxoff_read(struct file *f, char __user *buf,
>> }
>>
>> while (size) {
>> - uint32_t value;
>> + u32 value = adev->gfx.gfx_off_state;
>> +
>> + r = put_user(value, (u32 *)buf);
>> + if (r)
>> + goto out;
>> +
>> + result += 4;
>> + buf += 4;
>> + *pos += 4;
>> + size -= 4;
>> + }
>> +
>> + r = result;
>> +out:
>> + pm_runtime_mark_last_busy(adev_to_drm(adev)->dev);
>> + pm_runtime_put_autosuspend(adev_to_drm(adev)->dev);
>> +
>> + return r;
>> +}
>> +
>> +static ssize_t amdgpu_debugfs_gfxoff_status_read(struct file *f, char __user *buf,
>> + size_t size, loff_t *pos)
>> +{
>> + struct amdgpu_device *adev = file_inode(f)->i_private;
>> + ssize_t result = 0;
>> + int r;
>> +
>> + if (size & 0x3 || *pos & 0x3)
>> + return -EINVAL;
>> +
>> + r = pm_runtime_get_sync(adev_to_drm(adev)->dev);
>> + if (r < 0) {
>> + pm_runtime_put_autosuspend(adev_to_drm(adev)->dev);
>> + return r;
>> + }
>> +
>> + while (size) {
>> + u32 value;
>>
>> r = amdgpu_get_gfx_off_status(adev, &value);
>> if (r)
>> goto out;
>>
>> - r = put_user(value, (uint32_t *)buf);
>> + r = put_user(value, (u32 *)buf);
>> if (r)
>> goto out;
>>
>> @@ -1206,6 +1243,12 @@ static const struct file_operations amdgpu_debugfs_gfxoff_fops = {
>> .llseek = default_llseek
>> };
>>
>> +static const struct file_operations amdgpu_debugfs_gfxoff_status_fops = {
>> + .owner = THIS_MODULE,
>> + .read = amdgpu_debugfs_gfxoff_status_read,
>> + .llseek = default_llseek
>> +};
>> +
>> static const struct file_operations *debugfs_regs[] = {
>> &amdgpu_debugfs_regs_fops,
>> &amdgpu_debugfs_regs2_fops,
>> @@ -1217,6 +1260,7 @@ static const struct file_operations *debugfs_regs[] = {
>> &amdgpu_debugfs_wave_fops,
>> &amdgpu_debugfs_gpr_fops,
>> &amdgpu_debugfs_gfxoff_fops,
>> + &amdgpu_debugfs_gfxoff_status_fops,
>> };
>>
>> static const char *debugfs_regs_names[] = {
>> @@ -1230,6 +1274,7 @@ static const char *debugfs_regs_names[] = {
>> "amdgpu_wave",
>> "amdgpu_gpr",
>> "amdgpu_gfxoff",
>> + "amdgpu_gfxoff_status",
>> };
>>
>> /**
>> --
>> 2.37.0
>>
