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

[Mukesh Ojha]

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@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 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");