linux-kernel - Re: [PATCH v6 4/5] firmware: qcom_scm: Refactor code to support multiple download mode

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Message-ID: <ZHEt2mrYpSMKBuIX@surfacebook>
Date:   Sat, 27 May 2023 01:08:26 +0300
From:   andy.shevchenko@...il.com
To:     Mukesh Ojha <quic_mojha@...cinc.com>
Cc:     agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
        linus.walleij@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org
Subject: Re: [PATCH v6 4/5] firmware: qcom_scm: Refactor code to support
 multiple download mode

Wed, Mar 29, 2023 at 01:16:51PM +0530, Mukesh Ojha kirjoitti:
> Currently on Qualcomm SoC, download_mode is enabled if
> CONFIG_QCOM_SCM_DOWNLOAD_MODE_DEFAULT is selected.
> 
> Refactor the code such that it supports multiple download
> modes and drop CONFIG_QCOM_SCM_DOWNLOAD_MODE_DEFAULT config
> instead, give interface to set the download mode from
> module parameter.

...

>  #include <linux/clk.h>
>  #include <linux/reset-controller.h>
>  #include <linux/arm-smccc.h>

> +#include <linux/kstrtox.h>

Can this be located after clk.h which makes (some) order in this block?

...

>  #define QCOM_DOWNLOAD_MODE_MASK 0x30
>  #define QCOM_DOWNLOAD_FULLDUMP	0x1
> +#define QCOM_DOWNLOAD_NODUMP	0x0

Okay, so you start backward ordering.
But see comments to the next patch.

...

>  		ret = qcom_scm_io_update_field(__scm->dload_mode_addr,
> -				QCOM_DOWNLOAD_MODE_MASK,
> -				enable ? QCOM_DOWNLOAD_FULLDUMP : 0);
> +				QCOM_DOWNLOAD_MODE_MASK, download_mode);

Can ping-pong style be avoided? I.e. do the right thing in the previous patch,
so you won't change lines that were introduced just before.

...

>  }
>  
> +

Stray change.

> +static int get_download_mode(char *buffer, const struct kernel_param *kp)
> +{
> +	int len = 0;
> +
> +	if (download_mode == QCOM_DOWNLOAD_FULLDUMP)
> +		len = sysfs_emit(buffer, "full\n");
> +	else if (download_mode == QCOM_DOWNLOAD_NODUMP)
> +		len = sysfs_emit(buffer, "off\n");
> +
> +	return len;

You can return directly.

Also, what about download_mode that doesn't fit to the above two?

> +}

...

> +static int set_download_mode(const char *val, const struct kernel_param *kp)
> +{
> +	u32 old = download_mode;
> +
> +	if (sysfs_streq(val, "full")) {
> +		download_mode = QCOM_DOWNLOAD_FULLDUMP;
> +	} else if (sysfs_streq(val, "off")) {
> +		download_mode = QCOM_DOWNLOAD_NODUMP;

NIH sysfs_match_string().

> +	} else if (kstrtouint(val, 0, &download_mode) ||
> +		   !(download_mode == 0 || download_mode == 1)) {
> +		download_mode = old;
> +		pr_err("qcom_scm: unknown download mode: %s\n", val);

> +		return -EINVAL;

Do not shadow the error code from kstrtouint() it can be different to this one.

> +	}
> +
> +	if (__scm)
> +		qcom_scm_set_download_mode(download_mode);
> +
> +	return 0;
> +}

...

Have you updated corresponding documentation about this parameter?
Or there is none?

-- 
With Best Regards,
Andy Shevchenko