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SubjectRe: [PATCH] clk: qcom: gfm-mux: use runtime pm while accessing registers
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On 21/03/2023 18:46, Stephen Boyd wrote:
> Quoting Srinivas Kandagatla (2023-03-21 10:57:58)
>> gfm mux driver does support runtime pm but we never use it while
>> accessing registers. Looks like this driver was getting lucky and
>> totally depending on other drivers to leave the clk on.
>>
>> Fix this by doing runtime pm while accessing registers.
>>
>> Fixes: a2d8f507803e ("clk: qcom: Add support to LPASS AUDIO_CC Glitch Free Mux clocks")
>> Cc: stable@vger.kernel.org
>> Reported-by: Amit Pundir <amit.pundir@linaro.org>
>
> Is there a link to the report?

https://www.spinics.net/lists/stable/msg638380.html

>
>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
>> ---
>> drivers/clk/qcom/lpass-gfm-sm8250.c | 29 ++++++++++++++++++++++++++++-
>> 1 file changed, 28 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/clk/qcom/lpass-gfm-sm8250.c b/drivers/clk/qcom/lpass-gfm-sm8250.c
>> index 96f476f24eb2..bcf0ea534f7f 100644
>> --- a/drivers/clk/qcom/lpass-gfm-sm8250.c
>> +++ b/drivers/clk/qcom/lpass-gfm-sm8250.c
>> @@ -38,14 +38,37 @@ struct clk_gfm {
>> static u8 clk_gfm_get_parent(struct clk_hw *hw)
>> {
>> struct clk_gfm *clk = to_clk_gfm(hw);
>> + int ret;
>> + u8 parent;
>> +
>> + ret = pm_runtime_resume_and_get(clk->priv->dev);
>> + if (ret < 0 && ret != -EACCES) {
>> + dev_err_ratelimited(clk->priv->dev,
>> + "pm_runtime_resume_and_get failed in %s, ret %d\n",
>> + __func__, ret);
>> + return ret;
>> + }
>> +
>> + parent = readl(clk->gfm_mux) & clk->mux_mask;
>> +
>> + pm_runtime_mark_last_busy(clk->priv->dev);
>>
>> - return readl(clk->gfm_mux) & clk->mux_mask;
>> + return parent;
>> }
>>
>> static int clk_gfm_set_parent(struct clk_hw *hw, u8 index)
>> {
>> struct clk_gfm *clk = to_clk_gfm(hw);
>> unsigned int val;
>> + int ret;
>> +
>> + ret = pm_runtime_resume_and_get(clk->priv->dev);
>
> Doesn't the clk framework already do this? Why do we need to do it
> again?

You are right, clk core already does do pm_runtime_resume_and_get for
set_parent.

this looks redundant here.


so we need only need to add this for get_parent

--srini
>
>> + if (ret < 0 && ret != -EACCES) {
>> + dev_err_ratelimited(clk->priv->dev,
>> + "pm_runtime_resume_and_get failed in %s, ret %d\n",
>> + __func__, ret);
>> + return ret;
>> + }
>>
>> val = readl(clk->gfm_mux);
>>

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