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

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Date:   Fri, 05 Jun 2020 13:36:21 +0530
From:   ppvk@...eaurora.org
To:     Sibi Sankar <sibis@...eaurora.org>
Cc:     Matthias Kaehlcke <mka@...omium.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 2020-06-05 00:04, Sibi Sankar wrote:
> 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.
> 
Sorry. i forget to remove this print on V2. i will address this in my 
next patch set.

> 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.

True. i will remove this too in my next patch set.