Re: [PATCH 2/2] drm/amd: Fetch the EDID from _DDC if available for eDP
On 1/29/2024 10:46, Jani Nikula wrote: On Mon, 29 Jan 2024, Mario Limonciello wrote: On 1/29/2024 03:39, Jani Nikula wrote: On Fri, 26 Jan 2024, Mario Limonciello wrote: diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c index 9caba10315a8..c7e1563a46d3 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c @@ -278,6 +278,11 @@ static void amdgpu_connector_get_edid(struct drm_connector *connector) struct amdgpu_device *adev = drm_to_adev(dev); struct amdgpu_connector *amdgpu_connector = to_amdgpu_connector(connector); + if (amdgpu_connector->edid) + return; + + /* if the BIOS specifies the EDID via _DDC, prefer this */ + amdgpu_connector->edid = amdgpu_acpi_edid(adev, connector); Imagine the EDID returned by acpi_video_get_edid() has edid->extensions bigger than 4. Of course it should not, but you have no guarantees, and it originates outside of the kernel. The real fix is to have the function return a struct drm_edid which tracks the allocation size separately. Unfortunately, it requires a bunch of changes along the way. We've mostly done it in i915, and I've sent a series to do this in drm/bridge [1]. Looking at it again, perhaps the ACPI code should just return a blob, and the drm code should have a helper to wrap that around struct drm_edid, so that the ACPI code does not have to depend on drm. Basic idea remains. I'd ideally like to split this stuff and Melissa's rework to be independent if possible. I'll see if that's actually feasible. Bottom line, we should stop using struct edid in drivers. They'll all parse the info differently, and from what I've seen, often wrong. Thanks for the feedback. In that case this specific change should probably rebase on the Melissa's work https://lore.kernel.org/amd-gfx/20240126163429.56714-1-m...@igalia.com/ after she takes into account the feedback. Let me ask you this though - do you think that after that's done should we let all drivers get EDID from BIOS as a priority? Or would you prefer that this is unique to amdgpu? If the reason for having this is that the panel EDID contains some garbage, that's certainly not unique to amdgpu... :p OK; maybe a helper in DRM that wraps the ACPI code then and amdgpu will use the helper for this series. I'm also thinking it makes sense to have a new /proc/cmdline setup option to ignore the BIOS for EDID. I'm hoping that since Windows uses _DDC that BIOS will be higher quality; but you know; BIOS =) Something like: 1) If user specifies on kernel command line and puts an EDID in /lib/firmware use that. 2) If BIOS has EDID in _DDC and it's eDP panel, use that. I think we should also look into this. We currently don't do this, and it might help with some machines. However, gut feeling says it's probably better to keep this as a per driver decision instead of trying to bolt it into drm helpers. OK; I'll wire up the helper and if you want to use in the future you can too then. BR, Jani. 3) Get panel EDID.
Re: [PATCH 2/2] drm/amd: Fetch the EDID from _DDC if available for eDP
On Mon, 29 Jan 2024, Mario Limonciello wrote: > On 1/29/2024 03:39, Jani Nikula wrote: >> On Fri, 26 Jan 2024, Mario Limonciello wrote: >>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c >>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c >>> index 9caba10315a8..c7e1563a46d3 100644 >>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c >>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c >>> @@ -278,6 +278,11 @@ static void amdgpu_connector_get_edid(struct >>> drm_connector *connector) >>> struct amdgpu_device *adev = drm_to_adev(dev); >>> struct amdgpu_connector *amdgpu_connector = >>> to_amdgpu_connector(connector); >>> >>> + if (amdgpu_connector->edid) >>> + return; >>> + >>> + /* if the BIOS specifies the EDID via _DDC, prefer this */ >>> + amdgpu_connector->edid = amdgpu_acpi_edid(adev, connector); >> >> Imagine the EDID returned by acpi_video_get_edid() has edid->extensions >> bigger than 4. Of course it should not, but you have no guarantees, and >> it originates outside of the kernel. >> >> The real fix is to have the function return a struct drm_edid which >> tracks the allocation size separately. Unfortunately, it requires a >> bunch of changes along the way. We've mostly done it in i915, and I've >> sent a series to do this in drm/bridge [1]. Looking at it again, perhaps the ACPI code should just return a blob, and the drm code should have a helper to wrap that around struct drm_edid, so that the ACPI code does not have to depend on drm. Basic idea remains. >> Bottom line, we should stop using struct edid in drivers. They'll all >> parse the info differently, and from what I've seen, often wrong. >> >> > > Thanks for the feedback. In that case this specific change should > probably rebase on the Melissa's work > https://lore.kernel.org/amd-gfx/20240126163429.56714-1-m...@igalia.com/ > after she takes into account the feedback. > > Let me ask you this though - do you think that after that's done should > we let all drivers get EDID from BIOS as a priority? Or would you > prefer that this is unique to amdgpu? If the reason for having this is that the panel EDID contains some garbage, that's certainly not unique to amdgpu... :p > Something like: > > 1) If user specifies on kernel command line and puts an EDID in > /lib/firmware use that. > 2) If BIOS has EDID in _DDC and it's eDP panel, use that. I think we should also look into this. We currently don't do this, and it might help with some machines. However, gut feeling says it's probably better to keep this as a per driver decision instead of trying to bolt it into drm helpers. BR, Jani. > 3) Get panel EDID. > -- Jani Nikula, Intel
Re: [PATCH 2/2] drm/amd: Fetch the EDID from _DDC if available for eDP
On 1/29/2024 03:39, Jani Nikula wrote:
On Fri, 26 Jan 2024, Mario Limonciello wrote:
Some manufacturers have intentionally put an EDID that differs from
the EDID on the internal panel on laptops.
Attempt to fetch this EDID if it exists and prefer it over the EDID
that is provided by the panel.
Signed-off-by: Mario Limonciello
---
drivers/gpu/drm/amd/amdgpu/amdgpu.h | 2 ++
drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c | 30 +++
.../gpu/drm/amd/amdgpu/amdgpu_connectors.c| 5
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 8 -
.../amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 7 +++--
5 files changed, 49 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index c5f3859fd682..99abe12567a4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1520,6 +1520,7 @@ int amdgpu_acpi_get_mem_info(struct amdgpu_device *adev,
int xcc_id,
void amdgpu_acpi_get_backlight_caps(struct amdgpu_dm_backlight_caps *caps);
bool amdgpu_acpi_should_gpu_reset(struct amdgpu_device *adev);
+void *amdgpu_acpi_edid(struct amdgpu_device *adev, struct drm_connector
*connector);
void amdgpu_acpi_detect(void);
void amdgpu_acpi_release(void);
#else
@@ -1537,6 +1538,7 @@ static inline int amdgpu_acpi_get_mem_info(struct
amdgpu_device *adev,
}
static inline void amdgpu_acpi_fini(struct amdgpu_device *adev) { }
static inline bool amdgpu_acpi_should_gpu_reset(struct amdgpu_device *adev) {
return false; }
+static inline void *amdgpu_acpi_edid(struct amdgpu_device *adev, struct
drm_connector *connector) { return NULL; }
static inline void amdgpu_acpi_detect(void) { }
static inline void amdgpu_acpi_release(void) { }
static inline bool amdgpu_acpi_is_power_shift_control_supported(void) {
return false; }
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
index e550067e5c5d..c106335f1f22 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
@@ -1380,6 +1380,36 @@ bool amdgpu_acpi_should_gpu_reset(struct amdgpu_device
*adev)
#endif
}
+/**
+ * amdgpu_acpi_edid
+ * @adev: amdgpu_device pointer
+ * @connector: drm_connector pointer
+ *
+ * Returns the EDID used for the internal panel if present, NULL otherwise.
+ */
+void *
+amdgpu_acpi_edid(struct amdgpu_device *adev, struct drm_connector *connector)
+{
+ struct drm_device *ddev = adev_to_drm(adev);
+ struct acpi_device *acpidev = ACPI_COMPANION(ddev->dev);
+ void *edid;
+ int r;
+
+ if (!acpidev)
+ return NULL;
+
+ if (connector->connector_type != DRM_MODE_CONNECTOR_eDP)
+ return NULL;
+
+ r = acpi_video_get_edid(acpidev, ACPI_VIDEO_DISPLAY_LCD, -1, );
+ if (r < 0) {
+ DRM_DEBUG_DRIVER("Failed to get EDID from ACPI: %d\n", r);
+ return NULL;
+ }
+
+ return kmemdup(edid, r, GFP_KERNEL);
+}
+
/*
* amdgpu_acpi_detect - detect ACPI ATIF/ATCS methods
*
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
index 9caba10315a8..c7e1563a46d3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
@@ -278,6 +278,11 @@ static void amdgpu_connector_get_edid(struct drm_connector
*connector)
struct amdgpu_device *adev = drm_to_adev(dev);
struct amdgpu_connector *amdgpu_connector =
to_amdgpu_connector(connector);
+ if (amdgpu_connector->edid)
+ return;
+
+ /* if the BIOS specifies the EDID via _DDC, prefer this */
+ amdgpu_connector->edid = amdgpu_acpi_edid(adev, connector);
Imagine the EDID returned by acpi_video_get_edid() has edid->extensions
bigger than 4. Of course it should not, but you have no guarantees, and
it originates outside of the kernel.
The real fix is to have the function return a struct drm_edid which
tracks the allocation size separately. Unfortunately, it requires a
bunch of changes along the way. We've mostly done it in i915, and I've
sent a series to do this in drm/bridge [1].
Bottom line, we should stop using struct edid in drivers. They'll all
parse the info differently, and from what I've seen, often wrong.
Thanks for the feedback. In that case this specific change should
probably rebase on the Melissa's work
https://lore.kernel.org/amd-gfx/20240126163429.56714-1-m...@igalia.com/
after she takes into account the feedback.
Let me ask you this though - do you think that after that's done should
we let all drivers get EDID from BIOS as a priority? Or would you
prefer that this is unique to amdgpu?
Something like:
1) If user specifies on kernel command line and puts an EDID in
/lib/firmware use that.
2) If BIOS has EDID in _DDC and it's eDP panel, use that.
3) Get panel EDID.
BR,
Jani.
[1]
Re: [PATCH 2/2] drm/amd: Fetch the EDID from _DDC if available for eDP
On Fri, 26 Jan 2024, Mario Limonciello wrote:
> Some manufacturers have intentionally put an EDID that differs from
> the EDID on the internal panel on laptops.
>
> Attempt to fetch this EDID if it exists and prefer it over the EDID
> that is provided by the panel.
>
> Signed-off-by: Mario Limonciello
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 2 ++
> drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c | 30 +++
> .../gpu/drm/amd/amdgpu/amdgpu_connectors.c| 5
> .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 8 -
> .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 7 +++--
> 5 files changed, 49 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index c5f3859fd682..99abe12567a4 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -1520,6 +1520,7 @@ int amdgpu_acpi_get_mem_info(struct amdgpu_device
> *adev, int xcc_id,
>
> void amdgpu_acpi_get_backlight_caps(struct amdgpu_dm_backlight_caps *caps);
> bool amdgpu_acpi_should_gpu_reset(struct amdgpu_device *adev);
> +void *amdgpu_acpi_edid(struct amdgpu_device *adev, struct drm_connector
> *connector);
> void amdgpu_acpi_detect(void);
> void amdgpu_acpi_release(void);
> #else
> @@ -1537,6 +1538,7 @@ static inline int amdgpu_acpi_get_mem_info(struct
> amdgpu_device *adev,
> }
> static inline void amdgpu_acpi_fini(struct amdgpu_device *adev) { }
> static inline bool amdgpu_acpi_should_gpu_reset(struct amdgpu_device *adev)
> { return false; }
> +static inline void *amdgpu_acpi_edid(struct amdgpu_device *adev, struct
> drm_connector *connector) { return NULL; }
> static inline void amdgpu_acpi_detect(void) { }
> static inline void amdgpu_acpi_release(void) { }
> static inline bool amdgpu_acpi_is_power_shift_control_supported(void) {
> return false; }
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> index e550067e5c5d..c106335f1f22 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> @@ -1380,6 +1380,36 @@ bool amdgpu_acpi_should_gpu_reset(struct amdgpu_device
> *adev)
> #endif
> }
>
> +/**
> + * amdgpu_acpi_edid
> + * @adev: amdgpu_device pointer
> + * @connector: drm_connector pointer
> + *
> + * Returns the EDID used for the internal panel if present, NULL otherwise.
> + */
> +void *
> +amdgpu_acpi_edid(struct amdgpu_device *adev, struct drm_connector *connector)
> +{
> + struct drm_device *ddev = adev_to_drm(adev);
> + struct acpi_device *acpidev = ACPI_COMPANION(ddev->dev);
> + void *edid;
> + int r;
> +
> + if (!acpidev)
> + return NULL;
> +
> + if (connector->connector_type != DRM_MODE_CONNECTOR_eDP)
> + return NULL;
> +
> + r = acpi_video_get_edid(acpidev, ACPI_VIDEO_DISPLAY_LCD, -1, );
> + if (r < 0) {
> + DRM_DEBUG_DRIVER("Failed to get EDID from ACPI: %d\n", r);
> + return NULL;
> + }
> +
> + return kmemdup(edid, r, GFP_KERNEL);
> +}
> +
> /*
> * amdgpu_acpi_detect - detect ACPI ATIF/ATCS methods
> *
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> index 9caba10315a8..c7e1563a46d3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> @@ -278,6 +278,11 @@ static void amdgpu_connector_get_edid(struct
> drm_connector *connector)
> struct amdgpu_device *adev = drm_to_adev(dev);
> struct amdgpu_connector *amdgpu_connector =
> to_amdgpu_connector(connector);
>
> + if (amdgpu_connector->edid)
> + return;
> +
> + /* if the BIOS specifies the EDID via _DDC, prefer this */
> + amdgpu_connector->edid = amdgpu_acpi_edid(adev, connector);
Imagine the EDID returned by acpi_video_get_edid() has edid->extensions
bigger than 4. Of course it should not, but you have no guarantees, and
it originates outside of the kernel.
The real fix is to have the function return a struct drm_edid which
tracks the allocation size separately. Unfortunately, it requires a
bunch of changes along the way. We've mostly done it in i915, and I've
sent a series to do this in drm/bridge [1].
Bottom line, we should stop using struct edid in drivers. They'll all
parse the info differently, and from what I've seen, often wrong.
BR,
Jani.
[1] https://patchwork.freedesktop.org/series/128149/
> if (amdgpu_connector->edid)
> return;
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index cd98b3565178..1faa21f542bd 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -6562,17 +6562,23 @@ static void amdgpu_dm_connector_funcs_force(struct
> drm_connector *connector)
> {
>
