Re: [PATCH] clk: qcom: dispcc-sc8280xp: Don't park mdp_clk_src at registration time

[Konrad Dybcio]

On 3/4/26 12:54 PM, Pengyu Luo wrote:
> On Wed, Mar 4, 2026 at 7:20 PM Konrad Dybcio
> <konrad.dybcio@xxxxxxxxxxxxxxxx> wrote:
>>
>> On 3/3/26 4:01 PM, Pengyu Luo wrote:
>>> Parking disp{0,1}_cc_mdss_mdp_clk_src clk broke simplefb on HUAWEI
>>> Gaokun3, the image will stuck at grey for seconds until msm takes
>>> over framebuffer. Use clk_rcg2_shared_no_init_park_ops to skip it.
>>
>> Do you have clk_ignore_unused/pd_ignore_unused in your cmdline?
>>
> 
> Yes, always.
> 
>> The sc8280xp-huawei-gaokun3.dts references no clocks in the simplefb
>> node, so if you're unlucky with timing, this is ""expected behavior""
>>
> 
> On gaokun, if simplefb holds the mdp clk, there will not be the early
> framebuffer, I can't see it. After seconds, msm initialized, the
> display would show logs.

I'm going to assume you don't have efifb.

Is there a chance it's because simplefb is waiting for dispcc to probe,
and by the time that happens, msm probes right away?

i.e. it seems like something like

https://lore.kernel.org/lkml/20220806163255.10404-1-markuss.broks@xxxxxxxxx/

would be better suited if you want to get logs early *and* you have a
panel driver that works anyway

> 
> Once I owned another sc8280xp device(Ntmer TW220 aka robo & kala), dsi
> didn't work at that time, to bring up the simplefb, the clk must be
> held and no parking. gaokun3 always requires no parking only.
> 
> BTW, I can see this grey flash without simplefb too. On x13s, if
> building msm as a module and not putting the module into the initial
> ramdisk, what happens?

Do you mean that in conjunction with dispcc-sc8280xp present in
initramfs?

Konrad