linux-kernel - Re: [PATCH] clk: qcom: apss-ipq-pll: use stromer ops for IPQ5018 to fix boot failure

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Message-ID: <8affb3d8-6210-43e6-8cbb-de28bdcf326a@linaro.org>
Date: Thu, 14 Mar 2024 15:00:02 +0100
From: Konrad Dybcio <konrad.dybcio@...aro.org>
To: Gabor Juhos <j4g8y7@...il.com>, Bjorn Andersson <andersson@...nel.org>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Sricharan Ramabadhran <quic_srichara@...cinc.com>,
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
 Gokul Sriram Palanisamy <quic_gokulsri@...cinc.com>
Cc: linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] clk: qcom: apss-ipq-pll: use stromer ops for IPQ5018 to
 fix boot failure



On 3/14/24 14:50, Gabor Juhos wrote:
> 2024. 03. 13. 19:36 keltezéssel, Konrad Dybcio írta:
>>
>>
>> On 3/11/24 16:06, Gabor Juhos wrote:
>>> Booting v6.8 results in a hang on various IPQ5018 based boards.
>>> Investigating the problem showed that the hang happens when the
>>> clk_alpha_pll_stromer_plus_set_rate() function tries to write
>>> into the PLL_MODE register of the APSS PLL.
>>>
>>> Checking the downstream code revealed that it uses [1] stromer
>>> specific operations for IPQ5018, whereas in the current code
>>> the stromer plus specific operations are used.
>>>
>>> The ops in the 'ipq_pll_stromer_plus' clock definition can't be
>>> changed since that is needed for IPQ5332, so add a new alpha pll
>>> clock declaration which uses the correct stromer ops and use this
>>> new clock for IPQ5018 to avoid the boot failure.
>>>
>>> 1.
>>> https://git.codelinaro.org/clo/qsdk/oss/kernel/linux-ipq-5.4/-/blob/NHSS.QSDK.12.4/drivers/clk/qcom/apss-ipq5018.c#L67
>>>
>>> Cc: stable@...r.kernel.org
>>> Fixes: 50492f929486 ("clk: qcom: apss-ipq-pll: add support for IPQ5018")
>>> Signed-off-by: Gabor Juhos <j4g8y7@...il.com>
>>> ---
>>> Based on v6.8.
>>> ---
>>>    drivers/clk/qcom/apss-ipq-pll.c | 20 +++++++++++++++++++-
>>>    1 file changed, 19 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/clk/qcom/apss-ipq-pll.c b/drivers/clk/qcom/apss-ipq-pll.c
>>> index 678b805f13d45..11f1ae59438f7 100644
>>> --- a/drivers/clk/qcom/apss-ipq-pll.c
>>> +++ b/drivers/clk/qcom/apss-ipq-pll.c
>>> @@ -55,6 +55,24 @@ static struct clk_alpha_pll ipq_pll_huayra = {
>>>        },
>>>    };
>>>    +static struct clk_alpha_pll ipq_pll_stromer = {
>>> +    .offset = 0x0,
>>> +    .regs = ipq_pll_offsets[CLK_ALPHA_PLL_TYPE_STROMER_PLUS],
>>
>> CLK_ALPHA_PLL_TYPE_STROMER?
> 
> I admit that using CLK_ALPHA_PLL_TYPE_STROMER would be less confusing. However
> 'ipq_pll_offsets' array has no entry for that enum, and given the fact that the
> CLK_ALPHA_PLL_TYPE_STROMER_PLUS entry uses the correct register offsets it makes
>   little sense to add another entry with the same offsets.
> 
> Although the 'clk_alpha_pll_regs' in clk-alpha-pll.c has an entry for
> CLK_ALPHA_PLL_TYPE_STROMER, but the offsets defined there are not 'exactly' the
> same as the ones defined locally in 'ipq_pll_offsets'. They will be identical if
> [1] gets accepted but we are not there yet.

Oh, I completely overlooked that this driver has its own array.. Hm..

I suppose it would make sense to rename these indices to IPQ_PLL_x to
help avoid such confusion..

Konrad