Re: [PATCH v2] of: Add videomode helper

Hi Sascha,

On Thursday 13 September 2012 13:19:54 Sascha Hauer wrote:

On Thu, Sep 13, 2012 at 01:54:07PM +0300, Tomi Valkeinen wrote:

quoted

On Wed, 2012-07-04 at 09:56 +0200, Sascha Hauer wrote:

quoted

This patch adds a helper function for parsing videomodes from the
devicetree. The videomode can be either converted to a struct
drm_display_mode or a struct fb_videomode.

I have more or less the same generic comment for this as for the power
sequences series discussed: this would add panel specific information
into DT data, instead of the driver handling it. But, as also discussed
in the thread, there are differing opinions on which way is better.

With the panel timings I think the approach of moving them into DT is
the best we can do. There are so many displays out there, patching the
kernel each time a customer comes with some new display is no fun.

For generic panels, sure, but for panels that require a specific driver (for 
instance because the panel implements vendor-specific comments) the mode(s) 
could be hardcoded in the panel driver.

quoted

quoted

+int of_get_video_mode(struct device_node *np, struct drm_display_mode
*dmode,
+		struct fb_videomode *fbmode);

From caller's point of view I think it'd make more sense to have
separate functions to get drm mode or fb mode. I don't think there's a
case where the caller would want both.

Ok, that makes sense.

quoted

Then again, even better would be to have a common video mode struct used
by both fb and drm... But I think that's been on the todo list of
Laurent for a long time already =).

Yes, indeed. We should go into that direction. We already realized that
we want to have ranges instead of fixed values for the timings.

-- 
Regards,

Laurent Pinchart