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

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Message-ID: <8865e3b00fce4f28264b60cd498fcf02@codeaurora.org>
Date:   Thu, 04 Jun 2020 16:43:49 +0530
From:   ppvk@...eaurora.org
To:     Sibi Sankar <sibis@...eaurora.org>
Cc:     bjorn.andersson@...aro.org, adrian.hunter@...el.com,
        robh+dt@...nel.org, ulf.hansson@...aro.org,
        vbadigan@...eaurora.org, sboyd@...nel.org,
        georgi.djakov@...aro.org, mka@...omium.org,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-mmc-owner@...r.kernel.org, rnayak@...eaurora.org,
        matthias@...omium.org, linux-arm-msm-owner@...r.kernel.org
Subject: Re: [PATCH V1 1/2] mmc: sdhci-msm: Add interconnect bandwidth scaling
 support

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@...eaurora.org>
>> ---
>>  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.

>> +
>>  	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);