linux-kernel - Re: [PATCH V5 3/3] firmware: scm: Modify only the download bits in TCSR register

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Message-ID: <5c56cc3c-13d0-d9d8-0209-5b6e8d7a4dac@quicinc.com>
Date:   Mon, 24 Jul 2023 12:05:45 -0700
From:   Elliot Berman <quic_eberman@...cinc.com>
To:     Kathiravan T <quic_kathirav@...cinc.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        "Mukesh Ojha" <quic_mojha@...cinc.com>,
        Kalle Valo <kvalo@...nel.org>,
        Loic Poulain <loic.poulain@...aro.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-gpio@...r.kernel.org>
CC:     <quic_srichara@...cinc.com>, <quic_sjaganat@...cinc.com>,
        <quic_anusha@...cinc.com>, <quic_saahtoma@...cinc.com>,
        Poovendhan Selvaraj <quic_poovendh@...cinc.com>
Subject: Re: [PATCH V5 3/3] firmware: scm: Modify only the download bits in
 TCSR register



On 7/20/2023 12:04 AM, Kathiravan T wrote:
> From: Mukesh Ojha <quic_mojha@...cinc.com>
> 
> 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: Poovendhan Selvaraj <quic_poovendh@...cinc.com>
> Signed-off-by: Poovendhan Selvaraj <quic_poovendh@...cinc.com>
> Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
> Signed-off-by: Kathiravan T <quic_kathirav@...cinc.com>
> ---
> Changes in V5:
> 	- Added the Signed-off-by tag for user Poovendhan
> 	- Dropped the macro QCOM_DOWNLOAD_MODE_SHIFT in the favor of
> 	  PREP_FIELD
> 
>   drivers/firmware/qcom_scm.c | 11 +++++++++--
>   1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index 104d86e49b97..3830dcf14326 100644
> --- a/drivers/firmware/qcom_scm.c
> +++ b/drivers/firmware/qcom_scm.c
> @@ -30,6 +30,10 @@ module_param(download_mode, bool, 0);
>   #define SCM_HAS_IFACE_CLK	BIT(1)
>   #define SCM_HAS_BUS_CLK		BIT(2)
>   
> +#define QCOM_DOWNLOAD_FULLDUMP		0x1
> +#define QCOM_DOWNLOAD_NODUMP		0x0
> +#define QCOM_DOWNLOAD_MODE_MASK		BIT(4)
> +

Can you update __qcom_scm_set_dload_mode to use the FIELD_PREP bits as 
well? Ideally, you should be able to have no duplicate logic in 
__qcom_scm_set_dload_mode and in qcom_scm_set_download_mode. Before your 
patch, it was duplicated and we probably should've had it de-duplicated. 
With this patch, the logic and constants used have diverged when they 
don't need to.

>   struct qcom_scm {
>   	struct device *dev;
>   	struct clk *core_clk;
> @@ -440,6 +444,7 @@ static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
>   static void qcom_scm_set_download_mode(bool enable)
>   {
>   	bool avail;
> +	int val;
>   	int ret = 0;
>   
>   	avail = __qcom_scm_is_call_available(__scm->dev,
> @@ -448,8 +453,10 @@ 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);
> +		val = enable ? QCOM_DOWNLOAD_FULLDUMP : QCOM_DOWNLOAD_NODUMP;
> +		ret = qcom_scm_io_update_field(__scm->dload_mode_addr,
> +					       QCOM_DOWNLOAD_MODE_MASK,
> +					       FIELD_PREP(QCOM_DOWNLOAD_MODE_MASK, val));
>   	} else {
>   		dev_err(__scm->dev,
>   			"No available mechanism for setting download mode\n");