Am 15.12.2016 um 13:33 schrieb Nath, Arindam:
-----Original Message----- From: Grazvydas Ignotas [mailto:notasas@xxxxxxxxx] Sent: Thursday, December 15, 2016 5:52 PM To: Nath, Arindam Cc: Emil Velikov; David Airlie; Deucher, Alexander; ML dri-devel; amd-gfx mailing list; Koenig, Christian Subject: Re: [PATCH 1/1] drm/amd/amdgpu: get maximum and used UVD handles (v3) On Thu, Dec 15, 2016 at 1:47 PM, Nath, Arindam <Arindam.Nath@xxxxxxx> wrote:-----Original Message----- From: Emil Velikov [mailto:emil.l.velikov@xxxxxxxxx] Sent: Thursday, December 15, 2016 5:01 PM To: Nath, Arindam Cc: David Airlie; Deucher, Alexander; amd-gfx mailing list; ML dri-devel; Koenig, Christian Subject: Re: [PATCH 1/1] drm/amd/amdgpu: get maximum and used UVD handles (v3) On 15 December 2016 at 07:30, Nath, Arindam <Arindam.Nath@xxxxxxx> wrote:-----Original Message----- From: Emil Velikov [mailto:emil.l.velikov@xxxxxxxxx] Sent: Wednesday, December 14, 2016 9:26 PM To: Nath, Arindam Cc: David Airlie; Deucher, Alexander; amd-gfx mailing list; ML dri-devel; Koenig, Christian Subject: Re: [PATCH 1/1] drm/amd/amdgpu: get maximum and usedUVDhandles (v3) On 12 December 2016 at 18:49, <arindam.nath@xxxxxxx> wrote:From: Arindam Nath <arindam.nath@xxxxxxx> Change History -------------- v3: changes suggested by Christian - Add a check for UVD IP block using AMDGPU_HW_IP_UVD query type. - Add a check for asic_type to be less than CHIP_POLARIS10 since starting Polaris, we support unlimited UVD instances. - Add kerneldoc style comment for amdgpu_uvd_used_handles(). v2: as suggested by Christian - Add a new query AMDGPU_INFO_NUM_HANDLES - Create a helper function to return the number of currently used UVD handles. - Modify the logic to count the number of used UVD handles since handles can be freed in non-linear fashion. v1: - User might want to query the maximum number of UVD instances supported by firmware. In addition to that, if there are multiple applications using UVD handles at the same time, he might also want to query the currently used number of handles. For this we add two variables max_handles and used_handles inside drm_amdgpu_info_hw_ip. So now an application (or libdrm) can use AMDGPU_INFO IOCTL with AMDGPU_INFO_HW_IP_INFO query type to get these values. Signed-off-by: Arindam Nath <arindam.nath@xxxxxxx> Reviewed-by: Christian König <christian.koenig@xxxxxxx> --- drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 21+++++++++++++++++++++drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c | 25+++++++++++++++++++++++++drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.h | 1 + include/uapi/drm/amdgpu_drm.h | 9 +++++++++ 4 files changed, 56 insertions(+) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.cb/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.cindex 174eb59..3273d8c 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c @@ -570,6 +570,27 @@ static int amdgpu_info_ioctl(struct drm_device*dev, void *data, struct drm_filereturn -EINVAL; } } + case AMDGPU_INFO_NUM_HANDLES: { + struct drm_amdgpu_info_num_handles handle; + + switch (info->query_hw_ip.type) { + case AMDGPU_HW_IP_UVD: + /* Starting Polaris, we support unlimited UVD handles */ + if (adev->asic_type < CHIP_POLARIS10) { + handle.uvd_max_handles = adev->uvd.max_handles; + handle.uvd_used_handles =amdgpu_uvd_used_handles(adev);+ + return copy_to_user(out, &handle, + min((size_t)size, sizeof(handle))) ? -EFAULT : 0; + } else { + return -EINVAL;Using EINVAL doesn't seem right here. As per man 3 ioctl EINVAL The request or arg argument is not valid for this device. A bit further down you can see the one you want. ENODEV The fildes argument refers to a valid STREAMS device, but the corresponding device driver does not support the ioctl() function.Emil, ENODEV would mean the driver does not support ioctl() itself. But inour case ioctl() is supported.Since we extract the query type from arg passed to ioctl(), and it is thisquery AMDGPU_INFO_NUM_HANDLES which is not supported by driver(forPolaris), doesn’t returning EINVAL make more sense here?Unless I'm reading the code incorrectly - CHIP_POLARIS10 and older do not have support the query. Thus ENODEV is the one you want to use. Furthermore EINVAL is (mostly) used to indicate incorrect input (failed input validation) which userspace uses to check if kernel is too old/does not support X.Actually, the code says only asics older than CHIP_POLARIS10 support thequery, beyond it doesn’t. Wouldn't it be cleaner to return INT_MAX or something like that? Right now the interface is inconsistent, it's failing the same way as if userspace passed something invalid, while (IMHO) it should just say "unlimited".We need to return an error no. consistent with what ioctl() expects to return. This will enable userspace to take corrective action (or no action at all) depending on the error code.
Well, we could return INT_MAX for the maximum numbers of handles to note that there is not limit, but I also prefer returning an error code to note that this won't work as expected.
Regarding which error code to return I think that Emil has the right idea here.
Returning -EINVAL usually means that userspace provided an invalid value, but in this case it doesn't matter which value the UMD provide all of them would be invalid because starting with Polaris the hardware/firmware simply doesn't work this way any more.
So using -ENODEV or maybe -ENODATA indeed sound like the right think to do here.
Regards, Christian.
Thanks, ArindamGražvydas_______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
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