diff mbox

drm: tilcdc: reduce max_width for revision 1

Message ID 1479748590-3962-2-git-send-email-bgolaszewski@baylibre.com (mailing list archive)
State New, archived
Headers show

Commit Message

Bartosz Golaszewski Nov. 21, 2016, 5:16 p.m. UTC
It has been determined that the highest resolution supported correctly
by LCDC rev1 is 800x600. Reduce the max_width value for rev1 to 800 in
crtc_max_width().

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Jyri Sarha Nov. 21, 2016, 5:26 p.m. UTC | #1
On 11/21/16 19:16, Bartosz Golaszewski wrote:
> It has been determined that the highest resolution supported correctly
> by LCDC rev1 is 800x600. Reduce the max_width value for rev1 to 800 in
> crtc_max_width().
> 

I don't think this is the right way to limit the supported video modes.
There is technically there is no such limit, is there?

If memory bandwidth is limiting the functionality of higher resolutions,
you should use "max-bandwidth" tilcdc device-tree property [1].

Cheers,
Jyri

[1] In "Documentation/devicetree/bindings/display/tilcdc/tilcdc.txt":
Optional properties:
 - max-bandwidth: The maximum pixels per second that the memory
   interface / lcd controller combination can sustain



> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
>  drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
> index dfe3dd0..9081de5 100644
> --- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
> +++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
> @@ -683,7 +683,7 @@ int tilcdc_crtc_max_width(struct drm_crtc *crtc)
>  	int max_width = 0;
>  
>  	if (priv->rev == 1)
> -		max_width = 1024;
> +		max_width = 800;
>  	else if (priv->rev == 2)
>  		max_width = 2048;
>  
>
Bartosz Golaszewski Nov. 21, 2016, 5:29 p.m. UTC | #2
2016-11-21 18:26 GMT+01:00 Jyri Sarha <jsarha@ti.com>:
> On 11/21/16 19:16, Bartosz Golaszewski wrote:
>> It has been determined that the highest resolution supported correctly
>> by LCDC rev1 is 800x600. Reduce the max_width value for rev1 to 800 in
>> crtc_max_width().
>>
>
> I don't think this is the right way to limit the supported video modes.
> There is technically there is no such limit, is there?
>
> If memory bandwidth is limiting the functionality of higher resolutions,
> you should use "max-bandwidth" tilcdc device-tree property [1].
>
> Cheers,
> Jyri
>

Will do, thanks.

Bartosz Golaszewski
diff mbox

Patch

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index dfe3dd0..9081de5 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -683,7 +683,7 @@  int tilcdc_crtc_max_width(struct drm_crtc *crtc)
 	int max_width = 0;
 
 	if (priv->rev == 1)
-		max_width = 1024;
+		max_width = 800;
 	else if (priv->rev == 2)
 		max_width = 2048;