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

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Date:   Thu, 04 Jun 2020 23:25:16 +0530
From:   Sibi Sankar <sibis@...eaurora.org>
To:     ppvk@...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,
        linux-kernel-owner@...r.kernel.org
Subject: Re: [PATCH V1 1/2] mmc: sdhci-msm: Add interconnect bandwidth scaling
 support

On 2020-06-04 16:43, ppvk@...eaurora.org 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@...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.

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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