linux-kernel - Re: [PATCH V4 5/5] firmware: scm: Modify only the DLOAD bit in TCSR register for download mode

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Message-ID: <eac46f7b-e1e3-12d8-9831-581ace0c3de3@quicinc.com>
Date:   Wed, 15 Feb 2023 20:47:21 +0530
From:   POOVENDHAN SELVARAJ <quic_poovendh@...cinc.com>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        <agross@...nel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <lee@...nel.org>,
        <catalin.marinas@....com>, <will@...nel.org>,
        <shawnguo@...nel.org>, <arnd@...db.de>,
        <marcel.ziswiler@...adex.com>, <robimarko@...il.com>,
        <dmitry.baryshkov@...aro.org>, <nfraprado@...labora.com>,
        <broonie@...nel.org>, <quic_gurus@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     <quic_srichara@...cinc.com>, <quic_gokulsri@...cinc.com>,
        <quic_sjaganat@...cinc.com>, <quic_kathirav@...cinc.com>,
        <quic_arajkuma@...cinc.com>, <quic_anusha@...cinc.com>,
        <quic_devipriy@...cinc.com>
Subject: Re: [PATCH V4 5/5] firmware: scm: Modify only the DLOAD bit in TCSR
 register for download mode


On 2/15/2023 4:25 PM, POOVENDHAN SELVARAJ wrote:
>
>
> On 2/14/2023 6:27 PM, Srinivas Kandagatla wrote:
>>
>>
>> On 14/02/2023 05:14, 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@...cinc.com>
>>> Signed-off-by: Anusha Rao <quic_anusha@...cinc.com>
>>> Co-developed-by: Kathiravan Thirumoorthy <quic_kathirav@...cinc.com>
>>> Signed-off-by: Kathiravan Thirumoorthy <quic_kathirav@...cinc.com>
>>> Signed-off-by: Poovendhan Selvaraj <quic_poovendh@...cinc.com>
>>> ---
>>>   Changes in V4:
>>>     - retain the orginal value of tcsr register when download mode
>>>       is not set
>>>
>>>   drivers/firmware/qcom_scm.c | 15 ++++++++++-----
>>>   1 file changed, 10 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
>>> index 468d4d5ab550..8a34b386ac3a 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);
>>
>> why not read the value here before setting the DLOAD Mode instead of 
>> doing it in qcom_scm_set_download_mode()?
>> that would make the code simple and readable.
dload_addr_val is used in both if and else if cases in 
qcom_scm_set_download_mode(),
so we read in qcom_scm_set_download_mode() function and pass to 
__qcom_scm_set_dload_mode().
>>
>>>         return qcom_scm_call_atomic(__scm->dev, &desc, NULL);
>>>   }
>>> @@ -426,15 +427,19 @@ 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);
>>> +
>> not checking ret value here before proceeding?
>>
Okay, sure..will address in next patch series.
>>>       if (avail) {
>>> -        ret = __qcom_scm_set_dload_mode(__scm->dev, enable);
>>> +        ret = __qcom_scm_set_dload_mode(__scm->dev, dload_addr_val, 
>>> 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_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");


Please excuse the format in Previous mail response.
Had some issues in email client and now it's fixed.

Regards,
Poovendhan S