Re: [PATCH V1 1/2] mmc: sdhci-msm: Add interconnect bandwidth scaling support

[Sibi Sankar]

On 2020-06-04 16:43, ppvk@xxxxxxxxxxxxxx wrote:
> Hi Sibi,
>
> Thanks for the review!!
>
> On 2020-06-03 17:22, Sibi Sankar wrote:
> > Hey Pradeep,
> > Thanks for the patch.
> >
> > On 2020-06-03 14:39, Pradeep P V K wrote:
> > > Interconnect bandwidth scaling support is now added as a
> > > part of OPP [1]. So, make sure interconnect driver is ready
> > > before handling interconnect scaling.
> > >
> > > This change is based on
> > > [1] [Patch v8] Introduce OPP bandwidth bindings
> > > (https://lkml.org/lkml/2020/5/12/493)
> > >
> > > [2] [Patch v3] mmc: sdhci-msm: Fix error handling
> > > for dev_pm_opp_of_add_table()
> > > (https://lkml.org/lkml/2020/5/5/491)
> > >
> > > Signed-off-by: Pradeep P V K <ppvk@xxxxxxxxxxxxxx>
> > > ---
> > >  drivers/mmc/host/sdhci-msm.c | 16 ++++++++++++++++
> > >  1 file changed, 16 insertions(+)
> > >
> > > diff --git a/drivers/mmc/host/sdhci-msm.c 
> > > b/drivers/mmc/host/sdhci-msm.c
> > > index b277dd7..bf95484 100644
> > > --- a/drivers/mmc/host/sdhci-msm.c
> > > +++ b/drivers/mmc/host/sdhci-msm.c
> > > @@ -14,6 +14,7 @@
> > >  #include <linux/slab.h>
> > >  #include <linux/iopoll.h>
> > >  #include <linux/regulator/consumer.h>
> > > +#include <linux/interconnect.h>
> > >
> > >  #include "sdhci-pltfm.h"
> > >  #include "cqhci.h"
> > > @@ -1999,6 +2000,7 @@ static int sdhci_msm_probe(struct 
> > > platform_device *pdev)
> > >  	struct sdhci_pltfm_host *pltfm_host;
> > >  	struct sdhci_msm_host *msm_host;
> > >  	struct clk *clk;
> > > +	struct icc_path *sdhc_path;
> > >  	int ret;
> > >  	u16 host_version, core_minor;
> > >  	u32 core_version, config;
> > > @@ -2070,6 +2072,20 @@ static int sdhci_msm_probe(struct 
> > > platform_device *pdev)
> > >  	}
> > >  	msm_host->bulk_clks[0].clk = clk;
> > >
> > > +	/* Make sure that ICC driver is ready for interconnect bandwdith
> > > +	 * scaling before registering the device for OPP.
> > > +	 */
> > > +	sdhc_path = of_icc_get(&pdev->dev, NULL);
> > > +	ret = PTR_ERR_OR_ZERO(sdhc_path);
> > > +	if (ret) {
> > > +		if (ret == -EPROBE_DEFER)
> > > +			dev_info(&pdev->dev, "defer icc path: %d\n", ret);
> > > +		else
> > > +			dev_err(&pdev->dev, "failed to get icc path:%d\n", ret);
> > > +		goto bus_clk_disable;
> > > +	}
> > > +	icc_put(sdhc_path);
> >
> > ret = dev_pm_opp_of_find_icc_paths(&pdev->dev, NULL);
> >
> > since there are multiple paths
> > described in the bindings you
> > should use ^^ instead and you
> > can drop temporary path as well.
> Ok. of_icc_get() used above is only to test if ICC driver is ready or
> not. I'm not
> really using the multiple paths here. Anyhow i will use
> dev_pm_opp_of_find_icc_paths()
> to get rid of some extra lines of code.

Using dev_pm_opp_of_find_icc_paths
with NULL passed acts as a way of
validating all the paths specified
in the device and also validates if
the opp-table has bw related bindings
as well.

> > > +
> > >  	msm_host->opp_table = dev_pm_opp_set_clkname(&pdev->dev, "core");
> > >  	if (IS_ERR(msm_host->opp_table)) {
> > >  		ret = PTR_ERR(msm_host->opp_table);

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