Re: [PATCH RESEND] clk: meson: pll: copy retry workaround from vendor driver

[Yu Tu <yu.tu@amlogic.com>]

On 2022/8/29 17:54, Jerome Brunet wrote:
> [ EXTERNAL EMAIL ]
> 
> 
> On Sun 14 Aug 2022 at 23:25, Heiner Kallweit <hkallweit1@gmail.com> wrote:
> 
>> On a S905X4-based system this call fails randomly.
>> The vendor driver has a retry mechanism and on my system
>> the second attempt is successful always.
>>
> 
> This reason looks a bit weak to me.
> I'd like AML team to comment on this PLL problem as I suspect it might
> relate to other PLL we have been seeing

First of all, we've had this problem before. But the probability is very 
low, most of the PLL will not lock when the chip is tested at high and 
low temperature.

Our actual code has retry mechanism to solve the above problem.

> 
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>> ---
>>   drivers/clk/meson/clk-pll.c | 12 ++++++++----
>>   1 file changed, 8 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c
>> index 9e55617bc..daa025b6d 100644
>> --- a/drivers/clk/meson/clk-pll.c
>> +++ b/drivers/clk/meson/clk-pll.c
>> @@ -320,12 +320,16 @@ static int meson_clk_pll_is_enabled(struct clk_hw *hw)
>>   
>>   static int meson_clk_pcie_pll_enable(struct clk_hw *hw)
>>   {
>> -	meson_clk_pll_init(hw);
>> +	int retries = 10;
>>   
>> -	if (meson_clk_pll_wait_lock(hw))
>> -		return -EIO;
>> +	do {
>> +		meson_clk_pll_init(hw);
>> +		if (!meson_clk_pll_wait_lock(hw))
>> +			return 0;
>> +		pr_info("Retry enabling PCIe PLL clock\n");
>> +	} while (--retries);
>>   
>> -	return 0;
>> +	return -EIO;
>>   }
>>   
>>   static int meson_clk_pll_enable(struct clk_hw *hw)
> 
> .

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