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

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Message-ID: <9fca774e-3519-4d0c-ba61-6b84965f36c2@quicinc.com>
Date: Thu, 1 Feb 2024 10:25:22 +0800
From: Tao Zhang <quic_taozha@...cinc.com>
To: Suzuki K Poulose <suzuki.poulose@....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 1/31/2024 6:02 PM, Suzuki K Poulose wrote:
> 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.

Sure.

Is it OK if I modify the code as follow and update to this patch directly?

     *val &= ~(TPDA_Pn_CR_DSBSIZE | TPDA_Pn_CR_CMBSIZE);

     if (drvdata->dsb_esize == 64)
         *val |= TPDA_Pn_CR_DSBSIZE;
     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);
     else if (drvdata->cmb_esize == 8)
         *val &= ~TPDA_Pn_CR_CMBSIZE;

Best,

Tao

>
> Suzuki
>
>
>