Re: [PATCH V2 3/5] firmware: scm: Modify only the DLOAD bit in TCSR register for download mode

[Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>]

On 01/02/2023 09:05, Poovendhan Selvaraj wrote:
> Add support to read-modify-write TCSR register to modify only DLOAD bit.
>
> 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>
> ---
>   drivers/firmware/qcom_scm.c | 12 ++++++++----
>   1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index 2000323722bf..e3435587a72d 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 +417,7 @@ 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 : 0;


It is not read-modify-write when enable == false, its just writing 0.

Is this intentional?


>   
>   	return qcom_scm_call_atomic(__scm->dev, &desc, NULL);
>   }
> @@ -426,15 +426,19 @@ 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);
> +
>   	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);
> +				enable ? dload_addr_val |
> +					QCOM_SCM_BOOT_SET_DLOAD_MODE : 0);

same here.


--srini

>   	} else {
>   		dev_err(__scm->dev,
>   			"No available mechanism for setting download mode\n");