[PATCH 5/6] drm: bridge: samsung-dsim: Support non-burst mode

[Marek Vasut]

On 4/17/23 13:57, Adam Ford wrote:
> On Sun, Apr 16, 2023 at 5:13 PM Marek Vasut <marex at denx.de> wrote:
>>
>> On 4/15/23 12:41, Adam Ford wrote:
>>> The high-speed clock is hard-coded to the burst-clock
>>> frequency specified in the device tree.  However, when
>>> using devices like certain bridge chips without burst mode
>>> and varying resolutions and refresh rates, it may be
>>> necessary to set the high-speed clock dynamically based
>>> on the desired pixel clock for the connected device.
>>
>> The link rate negotiation should happen internally between the nearest
>> bridge and DSIM, so please add that to DRM core instead of hacking
>> around it by tweaking the HS clock again.
> 
> I thought you tried to add something like this before and had some resistance.

Yes, all my attempts were rejected by a single reviewer. I suspended my 
efforts in that area for now.

> The Pixel clock is set by the bridge already without any new code
> added to the DRM core..  I am just reading that value that's there,
> and setting the clock accordingly.  I don't see how this is a hack.

Assume you have a DSI-to-HDMI bridge attached to your DSIM bridge, it 
operates in non-burst mode, like ADV7533 . How would you configure the 
HS clock rate for such a bridge in DT ? (hint: you cannot, because the 
required clock comes from the EDID, which may not be available just yet)