linux-kernel - Re: [PATCH V2 1/2] mmc: sdhci-msm: Add interconnect bandwidth scaling support

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Message-ID: <23d6da79d604ce5113d90a2adab17483@codeaurora.org>
Date:   Fri, 05 Jun 2020 00:04:02 +0530
From:   Sibi Sankar <sibis@...eaurora.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Pradeep P V K <ppvk@...eaurora.org>, 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, 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
Subject: Re: [PATCH V2 1/2] mmc: sdhci-msm: Add interconnect bandwidth scaling
 support

On 2020-06-04 22:39, Matthias Kaehlcke wrote:
> On Thu, Jun 04, 2020 at 04:44:42PM +0530, 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 | 13 +++++++++++++
>>  1 file changed, 13 insertions(+)
>> 
>> diff --git a/drivers/mmc/host/sdhci-msm.c 
>> b/drivers/mmc/host/sdhci-msm.c
>> index b277dd7..a13ff1b 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"
>> @@ -2070,6 +2071,18 @@ 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.
>> +	 */
>> +	ret = dev_pm_opp_of_find_icc_paths(&pdev->dev, NULL);
>> +	if (ret) {
>> +		if (ret == -EPROBE_DEFER)
>> +			dev_info(&pdev->dev, "defer icc path: %d\n", ret);
> 
> I already commented on this on v1:
> 
>   This log seems to add little more than noise, or are there particular 
> reasons
>   why it is useful in this driver? Most drivers just return silently in 
> case of
>   deferred probing.
> 
> If you think the log is really needed please explain why.

Both the err logs seem redundant.
EPROBE_DEFERS are rather readily
noticeable through the return val.
dev_.._find_icc_paths already prints
err messages when we fail to get icc
paths.


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