linux-kernel - Re: [PATCH V2 12/15] coresight: tmc: keep track of memory width

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Date:	Fri, 15 Apr 2016 10:10:57 -0600
From:	Mathieu Poirier <mathieu.poirier@...aro.org>
To:	Suzuki K Poulose <Suzuki.Poulose@....com>
Cc:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 12/15] coresight: tmc: keep track of memory width

On 14 April 2016 at 05:19, Suzuki K Poulose <Suzuki.Poulose@....com> wrote:
> On 12/04/16 18:54, Mathieu Poirier wrote:
>>
>> Accessing the HW configuration register each time the memory
>> width is needed simply doesn't make sense.  It is much more
>> efficient to read the value once and keep a reference for
>> later use.
>>
>> Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
>> ---
>>   drivers/hwtracing/coresight/coresight-tmc-etf.c | 8 +++-----
>>   drivers/hwtracing/coresight/coresight-tmc.c     | 1 +
>>   drivers/hwtracing/coresight/coresight-tmc.h     | 2 ++
>>   3 files changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c
>> b/drivers/hwtracing/coresight/coresight-tmc-etf.c
>> index 50d32e8ef4ea..a440784e3b27 100644
>> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
>> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
>> @@ -41,18 +41,16 @@ void tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
>>
>>   static void tmc_etb_dump_hw(struct tmc_drvdata *drvdata)
>>   {
>> -       enum tmc_mem_intf_width memwidth;
>>         u8 memwords;
>>         char *bufp;
>>         u32 read_data;
>>         int i;
>>
>> -       memwidth = BMVAL(readl_relaxed(drvdata->base + CORESIGHT_DEVID),
>> 8, 10);
>> -       if (memwidth == TMC_MEM_INTF_WIDTH_32BITS)
>> +       if (drvdata->memwidth == TMC_MEM_INTF_WIDTH_32BITS)
>>                 memwords = 1;
>> -       else if (memwidth == TMC_MEM_INTF_WIDTH_64BITS)
>> +       else if (drvdata->memwidth == TMC_MEM_INTF_WIDTH_64BITS)
>>                 memwords = 2;
>> -       else if (memwidth == TMC_MEM_INTF_WIDTH_128BITS)
>> +       else if (drvdata->memwidth == TMC_MEM_INTF_WIDTH_128BITS)
>>                 memwords = 4;
>
>
>
>>   struct tmc_drvdata {
>> @@ -118,6 +119,7 @@ struct tmc_drvdata {
>>         u32                     size;
>>         local_t                 mode;
>>         enum tmc_config_type    config_type;
>> +       enum tmc_mem_intf_width memwidth;
>
>
> Could we not store the converted memwords here, instead of the enum value
> here
> and convert it every time we access it ?

Sure, I can fix that.

Thanks for the review,
Mathieu

>
> Cheers
> Suzuki