linux-kernel - Re: [PATCH V5 3/3] firmware: scm: Modify only the download bits in TCSR register

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Message-ID: <6b6a383f-4a3a-e55b-dc86-b1abb8c7acab@quicinc.com>
Date:   Tue, 25 Jul 2023 15:54:17 +0530
From:   Kathiravan T <quic_kathirav@...cinc.com>
To:     Elliot Berman <quic_eberman@...cinc.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        "Mukesh Ojha" <quic_mojha@...cinc.com>,
        Kalle Valo <kvalo@...nel.org>,
        Loic Poulain <loic.poulain@...aro.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-gpio@...r.kernel.org>
CC:     <quic_srichara@...cinc.com>, <quic_sjaganat@...cinc.com>,
        <quic_anusha@...cinc.com>, <quic_saahtoma@...cinc.com>,
        Poovendhan Selvaraj <quic_poovendh@...cinc.com>
Subject: Re: [PATCH V5 3/3] firmware: scm: Modify only the download bits in
 TCSR register


On 7/25/2023 12:35 AM, Elliot Berman wrote:
>
>
> On 7/20/2023 12:04 AM, Kathiravan T wrote:
>> From: Mukesh Ojha <quic_mojha@...cinc.com>
>>
>> CrashDump collection is based on the DLOAD bit of TCSR register. To 
>> retain
>> other bits, we read the register and modify only the DLOAD bit as the
>> other bits have their own significance.
>>
>> Co-developed-by: Poovendhan Selvaraj <quic_poovendh@...cinc.com>
>> Signed-off-by: Poovendhan Selvaraj <quic_poovendh@...cinc.com>
>> Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
>> Signed-off-by: Kathiravan T <quic_kathirav@...cinc.com>
>> ---
>> Changes in V5:
>>     - Added the Signed-off-by tag for user Poovendhan
>>     - Dropped the macro QCOM_DOWNLOAD_MODE_SHIFT in the favor of
>>       PREP_FIELD
>>
>>   drivers/firmware/qcom_scm.c | 11 +++++++++--
>>   1 file changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
>> index 104d86e49b97..3830dcf14326 100644
>> --- a/drivers/firmware/qcom_scm.c
>> +++ b/drivers/firmware/qcom_scm.c
>> @@ -30,6 +30,10 @@ module_param(download_mode, bool, 0);
>>   #define SCM_HAS_IFACE_CLK    BIT(1)
>>   #define SCM_HAS_BUS_CLK        BIT(2)
>>   +#define QCOM_DOWNLOAD_FULLDUMP        0x1
>> +#define QCOM_DOWNLOAD_NODUMP        0x0
>> +#define QCOM_DOWNLOAD_MODE_MASK        BIT(4)
>> +
>
> Can you update __qcom_scm_set_dload_mode to use the FIELD_PREP bits as 
> well? Ideally, you should be able to have no duplicate logic in 
> __qcom_scm_set_dload_mode and in qcom_scm_set_download_mode. Before 
> your patch, it was duplicated and we probably should've had it 
> de-duplicated. With this patch, the logic and constants used have 
> diverged when they don't need to.


Sure, will check this.


>
>>   struct qcom_scm {
>>       struct device *dev;
>>       struct clk *core_clk;
>> @@ -440,6 +444,7 @@ static int __qcom_scm_set_dload_mode(struct 
>> device *dev, bool enable)
>>   static void qcom_scm_set_download_mode(bool enable)
>>   {
>>       bool avail;
>> +    int val;
>>       int ret = 0;
>>         avail = __qcom_scm_is_call_available(__scm->dev,
>> @@ -448,8 +453,10 @@ static void qcom_scm_set_download_mode(bool enable)
>>       if (avail) {
>>           ret = __qcom_scm_set_dload_mode(__scm->dev, enable);
>>       } else if (__scm->dload_mode_addr) {
>> -        ret = qcom_scm_io_writel(__scm->dload_mode_addr,
>> -                enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0);
>> +        val = enable ? QCOM_DOWNLOAD_FULLDUMP : QCOM_DOWNLOAD_NODUMP;
>> +        ret = qcom_scm_io_update_field(__scm->dload_mode_addr,
>> +                           QCOM_DOWNLOAD_MODE_MASK,
>> +                           FIELD_PREP(QCOM_DOWNLOAD_MODE_MASK, val));
>>       } else {
>>           dev_err(__scm->dev,
>>               "No available mechanism for setting download mode\n");