Re: [PATCH] soc: qcom: llcc: Add llcc device availability check

[Mukesh Ojha]

On 3/7/2024 3:51 PM, Krzysztof Kozlowski wrote:
> On 20/02/2024 13:28, Mukesh Ojha wrote:
> > When llcc driver is enabled  and llcc device is not
> > physically there on the SoC, client can get
> > -EPROBE_DEFER on calling llcc_slice_getd() and it
> > is possible they defer forever.
>
> Please wrap commit message according to Linux coding style / submission
> process (neither too early nor over the limit):
> https://elixir.bootlin.com/linux/v6.4-rc1/source/Documentation/process/submitting-patches.rst#L597

Noted.

> > Let's add a check device availabilty and set the
> > appropriate applicable error in drv_data.
> >
> > Signed-off-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
> > ---
> >   drivers/soc/qcom/llcc-qcom.c | 23 ++++++++++++++++++++++-
> >   1 file changed, 22 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/soc/qcom/llcc-qcom.c b/drivers/soc/qcom/llcc-qcom.c
> > index 4ca88eaebf06..cb336b183bba 100644
> > --- a/drivers/soc/qcom/llcc-qcom.c
> > +++ b/drivers/soc/qcom/llcc-qcom.c
> > @@ -769,6 +769,27 @@ static const struct qcom_sct_config x1e80100_cfgs = {
> >   };
> >   
> >   static struct llcc_drv_data *drv_data = (void *) -EPROBE_DEFER;
> > +static DEFINE_MUTEX(dev_avail);
> > +
> > +static bool is_llcc_device_available(void)
> > +{
> > +	static struct llcc_drv_data *ptr;
> > +
> > +	mutex_lock(&dev_avail);
> > +	if (!ptr) {
> > +		struct device_node *node;
> > +
> > +		node = of_find_node_by_name(NULL, "system-cache-controller");
>
> Why do you look names by name? This create undocumented ABI. >
> NAK (also for any future uses of such of_find_node_by_name()).

I agree, what if we add a common compatible string like qcom,llcc to all 
llcc supported SoCs.

-Mukesh
> Best regards,
> Krzysztof