Re: [PATCH 2/2] clk: qcom: dispcc-sdm845: park disp_cc_mdss_mdp_clk_src

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 09/12/2021 21:40, Bjorn Andersson wrote:
> On Tue 07 Dec 18:22 PST 2021, Dmitry Baryshkov wrote:
> 
>> To stop disp_cc_mdss_mdp_clk_src from getting stuck during boot if it
>> was enabled by the bootloader, part it to the TCXO clock source.
>>
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>> ---
>>   drivers/clk/qcom/dispcc-sdm845.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/clk/qcom/dispcc-sdm845.c b/drivers/clk/qcom/dispcc-sdm845.c
>> index 735adfefc379..f2afbba7bc72 100644
>> --- a/drivers/clk/qcom/dispcc-sdm845.c
>> +++ b/drivers/clk/qcom/dispcc-sdm845.c
>> @@ -858,6 +858,9 @@ static int disp_cc_sdm845_probe(struct platform_device *pdev)
>>   
>>   	clk_fabia_pll_configure(&disp_cc_pll0, regmap, &disp_cc_pll0_config);
>>   
>> +	/* Park disp_cc_mdss_mdp_clk_src */
>> +	clk_rcg2_park_safely(regmap, 0x2088, 0);
> 
> Today booting the system with "clk_ignore_unused" will give you a
> working efifb up until the point where the display driver kicks in and
> reinitializes the hardware state - which during development might be
> indefinite.
> 
> If we blindly cut the mdp_clk_src here that will no longer be possible.

Yep. There is an opposite issue. I was getting the rcg2 stuck messages 
_before_ the clk_disable_unused kicks in. So we definitely need 
something more complex than both our proposals. Not to mention that 
Steev tested that this does not fix the issue on C630.

> 
> Regards,
> Bjorn
> 
>> +
>>   	/* Enable hardware clock gating for DSI and MDP clocks */
>>   	regmap_update_bits(regmap, 0x8000, 0x7f0, 0x7f0);
>>   
>> -- 
>> 2.33.0
>>


-- 
With best wishes
Dmitry