Re: [PATCH] drm/omap: Migrate minimum FCK/PCK ratio from Kconfig to dts

[Andrew F. Davis]

On 5/28/19 4:11 AM, Tomi Valkeinen wrote:
> Hi,
> 
> On 10/05/2019 22:42, Adam Ford wrote:
>> Currently the source code is compiled using hard-coded values
>> from CONFIG_OMAP2_DSS_MIN_FCK_PER_PCK. This patch allows this
>> clock divider value to be moved to the device tree and be changed
>> without having to recompile the kernel.
>>
>> Signed-off-by: Adam Ford <aford173@xxxxxxxxx>
> 
> I understand why you want to do this, but I'm not sure it's a good idea.
> It's really something the driver should figure out, and if we add it to
> the DT, it effectively becomes an ABI.
> 
> That said... I'm not sure how good of a job the driver could ever do, as
> it can't know the future scaling needs of the userspace at the time it
> is configuring the clock. And so, I'm not nacking this patch, but I
> don't feel very good about this patch...
> 
> The setting also affects all outputs (exluding venc), which may not be
> what the user wants. Then again, I think this setting is really only
> needed on OMAP2 & 3, which have only a single output. But that's the
> same with the current kconfig option, of course.
> 
> So, the current CONFIG_OMAP2_DSS_MIN_FCK_PER_PCK is an ugly hack, in my
> opinion, and moving it to DT makes it a worse hack =). But I don't have
> any good suggestions either.
> 


Module param?

Andrew


> ÂTomi
>