Re: [PATCH V5 5/5] firmware: scm: Modify only the DLOAD bit in TCSR register for download mode

[Mukesh Ojha <quic_mojha@quicinc.com>]

On 2/16/2023 7:30 PM, Mukesh Ojha wrote:
> 
> 
> On 2/16/2023 5:30 PM, Poovendhan Selvaraj wrote:
>> 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: Anusha Rao <quic_anusha@quicinc.com>
>> Signed-off-by: Anusha Rao <quic_anusha@quicinc.com>
>> Co-developed-by: Kathiravan Thirumoorthy <quic_kathirav@quicinc.com>
>> Signed-off-by: Kathiravan Thirumoorthy <quic_kathirav@quicinc.com>
>> Signed-off-by: Poovendhan Selvaraj <quic_poovendh@quicinc.com>
>> ---
>>   Changes in V5:
>>     - checking the return value in qcom_scm_set_download_mode function as
>>       suggested by Srinivas Kandagatla
>>
>>   Changes in V4:
>>     - retain the orginal value of tcsr register when download mode
>>       is not set
>>
>>   drivers/firmware/qcom_scm.c | 21 ++++++++++++++++-----
>>   1 file changed, 16 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
>> index 468d4d5ab550..d88c5f14bd54 100644
>> --- a/drivers/firmware/qcom_scm.c
>> +++ b/drivers/firmware/qcom_scm.c
>> @@ -407,7 +407,7 @@ int qcom_scm_set_remote_state(u32 state, u32 id)
>>   }
>>   EXPORT_SYMBOL(qcom_scm_set_remote_state);
>> -static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
>> +static int __qcom_scm_set_dload_mode(struct device *dev, u32 val, 
>> bool enable)
>>   {
>>       struct qcom_scm_desc desc = {
>>           .svc = QCOM_SCM_SVC_BOOT,
>> @@ -417,7 +417,8 @@ static int __qcom_scm_set_dload_mode(struct device 
>> *dev, bool enable)
>>           .owner = ARM_SMCCC_OWNER_SIP,
>>       };
>> -    desc.args[1] = enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0;
>> +    desc.args[1] = enable ? val | QCOM_SCM_BOOT_SET_DLOAD_MODE :
>> +                val & ~(QCOM_SCM_BOOT_SET_DLOAD_MODE);
>>       return qcom_scm_call_atomic(__scm->dev, &desc, NULL);
>>   }
>> @@ -426,15 +427,25 @@ static void qcom_scm_set_download_mode(bool enable)
>>   {
>>       bool avail;
>>       int ret = 0;
>> +    u32 dload_addr_val;
>>       avail = __qcom_scm_is_call_available(__scm->dev,
>>                            QCOM_SCM_SVC_BOOT,
>>                            QCOM_SCM_BOOT_SET_DLOAD_MODE);
>> +    ret = qcom_scm_io_readl(__scm->dload_mode_addr, &dload_addr_val);
>> +
>> +    if (ret) {
>> +        dev_err(__scm->dev,
>> +            "failed to read dload mode address value: %d\n", ret);
>> +        return;
>> +    }
>> +
>>       if (avail) {
>> -        ret = __qcom_scm_set_dload_mode(__scm->dev, enable);
>> +        ret = __qcom_scm_set_dload_mode(__scm->dev, dload_addr_val, 
>> enable);
> 
> Did you test this on a target where it comes under this if statement? 
> does it really need to know dload_mode_addr for this target ?


Can we do something like this? I would let other review as well.

--------------------------------------->0-------------------------------------------
diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index cdbfe54..26b7eda 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -419,6 +419,7 @@ static void qcom_scm_set_download_mode(bool enable)
  {
         bool avail;
         int ret = 0;
+       u32 dload_addr_val;

         avail = __qcom_scm_is_call_available(__scm->dev,
                                              QCOM_SCM_SVC_BOOT,
@@ -426,8 +427,16 @@ 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);
+               ret = qcom_scm_io_readl(__scm->dload_mode_addr, 
&dload_addr_val);
+               if (ret) {
+                       dev_err(__scm->dev,
+                               "failed to read dload mode address 
value: %d\n", ret);
+                       return;
+               }
+
+               ret = qcom_scm_io_writel(__scm->dload_mode_addr, enable ?
+                               dload_addr_val | 
QCOM_SCM_BOOT_SET_DLOAD_MODE :
+                               dload_addr_val & 
~(QCOM_SCM_BOOT_SET_DLOAD_MODE));
         } else {
                 dev_err(__scm->dev,
                         "No available mechanism for setting download 
mode\n");

-Mukesh
> 
> -Mukesh
>>       } else if (__scm->dload_mode_addr) {
>> -        ret = qcom_scm_io_writel(__scm->dload_mode_addr,
>> -                enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0);
>> +        ret = qcom_scm_io_writel(__scm->dload_mode_addr, enable ?
>> +                dload_addr_val | QCOM_SCM_BOOT_SET_DLOAD_MODE :
>> +                dload_addr_val & ~(QCOM_SCM_BOOT_SET_DLOAD_MODE));
>>       } else {
>>           dev_err(__scm->dev,
>>               "No available mechanism for setting download mode\n");

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