linux-kernel - Re: [PATCH v5 05/10] coresight-tpda: Add support to configure CMB element

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Message-ID: <1f5a7c7b-56de-4f19-9d48-652ae6efe50f@arm.com>
Date: Wed, 31 Jan 2024 10:02:58 +0000
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Tao Zhang <quic_taozha@...cinc.com>,
 Mathieu Poirier <mathieu.poirier@...aro.org>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Konrad Dybcio <konradybcio@...il.com>, Mike Leach <mike.leach@...aro.org>,
 Rob Herring <robh+dt@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc: Jinlong Mao <quic_jinlmao@...cinc.com>, Leo Yan <leo.yan@...aro.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, coresight@...ts.linaro.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org, Tingwei Zhang <quic_tingweiz@...cinc.com>,
 Yuanfang Zhang <quic_yuanfang@...cinc.com>,
 Trilok Soni <quic_tsoni@...cinc.com>, Song Chai <quic_songchai@...cinc.com>,
 linux-arm-msm@...r.kernel.org, andersson@...nel.org
Subject: Re: [PATCH v5 05/10] coresight-tpda: Add support to configure CMB
 element

On 31/01/2024 01:39, Tao Zhang wrote:
> 
> On 1/30/2024 8:35 PM, Suzuki K Poulose wrote:
>> On 30/01/2024 09:02, Tao Zhang wrote:
>>> Read the CMB element size from the device tree. Set the register
>>> bit that controls the CMB element size of the corresponding port.
>>>
>>> Reviewed-by: James Clark <james.clark@....com>
>>> Signed-off-by: Tao Zhang <quic_taozha@...cinc.com>
>>> Signed-off-by: Mao Jinlong <quic_jinlmao@...cinc.com>
>>> ---
>>>   drivers/hwtracing/coresight/coresight-tpda.c | 123 +++++++++++--------
>>>   drivers/hwtracing/coresight/coresight-tpda.h |   6 +
>>>   2 files changed, 79 insertions(+), 50 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/coresight-tpda.c 
>>> b/drivers/hwtracing/coresight/coresight-tpda.c
>>> index 4ac954f4bc13..fcddff3ded81 100644
>>> --- a/drivers/hwtracing/coresight/coresight-tpda.c
>>> +++ b/drivers/hwtracing/coresight/coresight-tpda.c
>>> @@ -18,6 +18,7 @@
>>>   #include "coresight-priv.h"
>>>   #include "coresight-tpda.h"
>>>   #include "coresight-trace-id.h"
>>> +#include "coresight-tpdm.h"
>>>     DEFINE_CORESIGHT_DEVLIST(tpda_devs, "tpda");
>>>   @@ -28,24 +29,57 @@ static bool coresight_device_is_tpdm(struct 
>>> coresight_device *csdev)
>>>               CORESIGHT_DEV_SUBTYPE_SOURCE_TPDM);
>>>   }
>>>   +static void tpdm_clear_element_size(struct coresight_device *csdev)
>>> +{
>>> +    struct tpda_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
>>> +
>>> +    drvdata->dsb_esize = 0;
>>> +    drvdata->cmb_esize = 0;
>>> +}
>>> +
>>> +static void tpda_set_element_size(struct tpda_drvdata *drvdata, u32 
>>> *val)
>>> +{
>>> +
>>
>>
>>
>>> +    if (drvdata->dsb_esize == 64)
>>> +        *val |= TPDA_Pn_CR_DSBSIZE;
>>
>> We don't seem to be clearing the fields we modify, before updating 
>> them. This may be OK in real world where the device connected to TPDA 
>> port
>> may not change. But it is always safer to clear the bits and set it.
>>
>> e.g.:
>>     *val &= ~(TPDA_Pn_CR_DSBSIZE | TPDA_Pn_CR_CMBSIZE);
>>
>>
>>
>>> +    else if (drvdata->dsb_esize == 32)
>>> +        *val &= ~TPDA_Pn_CR_DSBSIZE;
>>> +
>>> +    if (drvdata->cmb_esize == 64)
>>> +        *val |= FIELD_PREP(TPDA_Pn_CR_CMBSIZE, 0x2);
>>> +    else if (drvdata->cmb_esize == 32)
>>> +        *val |= FIELD_PREP(TPDA_Pn_CR_CMBSIZE, 0x1);
>>
>> Similarly here ^^^. I am happy to fix it up if you are OK with it 
>> (unless there are other changes that need a respin)
> 
> Thank you. I would be very grateful if you could help for this.

Given, you need to respin, please incorporate this change too.

Suzuki