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

[Srinivas Kandagatla]

On 15/02/2023 10:55, 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@xxxxxxxxxxx>
> > > Signed-off-by: Anusha Rao <quic_anusha@xxxxxxxxxxx>
> > > Co-developed-by: Kathiravan Thirumoorthy <quic_kathirav@xxxxxxxxxxx>
> > > Signed-off-by: Kathiravan Thirumoorthy <quic_kathirav@xxxxxxxxxxx>
> > > Signed-off-by: Poovendhan Selvaraj <quic_poovendh@xxxxxxxxxxx>
> > > ---
> > >   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().

that is fine as it is, I missread else part as calling 
__qcom_scm_set_dload_mode() too.

just check the ret value should be good.

--srini


>    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 {
>
> > >         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");
>
> Regards,
> Poovendhan S