Date: Fri, 22 Aug 2025 12:26:54 -0400
From: Rodrigo Vivi <rodrigo.vivi@intel.com>
To: Stuart Summers <stuart.summers@intel.com>
CC: <intel-xe@lists.freedesktop.org>, <raag.jadav@intel.com>, Jonathan Cavitt
 <jonathan.cavitt@intel.com>
Subject: Re: [PATCH] drm/xe/pcode: Initialize data0 for pcode read routine
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On Tue, Aug 19, 2025 at 08:10:54PM +0000, Stuart Summers wrote:
> There are two registers filled in when reading data from
> pcode besides the mailbox itself. Currently, we allow a NULL
> value for the second of these two (data1) and assume the first
> is defined. However, many of the routines that are calling
> this function assume that pcode will ignore the value being
> passed in and so leave that first value (data0) defined but
> uninitialized. To be safe, make sure this value is always
> initialized to something (0 generally) in the event pcode
> behavior changes and starts using this value.
> 
> v2: Fix sob/author

pushed to drm-xe-next. Thank you all

> 
> Signed-off-by: Stuart Summers <stuart.summers@intel.com>
> Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_device_sysfs.c | 8 ++++----
>  drivers/gpu/drm/xe/xe_hwmon.c        | 8 ++++----
>  drivers/gpu/drm/xe/xe_vram_freq.c    | 4 ++--
>  3 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_device_sysfs.c b/drivers/gpu/drm/xe/xe_device_sysfs.c
> index bd9015761aa0..6ee422594b56 100644
> --- a/drivers/gpu/drm/xe/xe_device_sysfs.c
> +++ b/drivers/gpu/drm/xe/xe_device_sysfs.c
> @@ -76,7 +76,7 @@ lb_fan_control_version_show(struct device *dev, struct device_attribute *attr, c
>  {
>  	struct xe_device *xe = pdev_to_xe_device(to_pci_dev(dev));
>  	struct xe_tile *root = xe_device_get_root_tile(xe);
> -	u32 cap, ver_low = FAN_TABLE, ver_high = FAN_TABLE;
> +	u32 cap = 0, ver_low = FAN_TABLE, ver_high = FAN_TABLE;
>  	u16 major = 0, minor = 0, hotfix = 0, build = 0;
>  	int ret;
>  
> @@ -115,7 +115,7 @@ lb_voltage_regulator_version_show(struct device *dev, struct device_attribute *a
>  {
>  	struct xe_device *xe = pdev_to_xe_device(to_pci_dev(dev));
>  	struct xe_tile *root = xe_device_get_root_tile(xe);
> -	u32 cap, ver_low = VR_CONFIG, ver_high = VR_CONFIG;
> +	u32 cap = 0, ver_low = VR_CONFIG, ver_high = VR_CONFIG;
>  	u16 major = 0, minor = 0, hotfix = 0, build = 0;
>  	int ret;
>  
> @@ -153,7 +153,7 @@ static int late_bind_create_files(struct device *dev)
>  {
>  	struct xe_device *xe = pdev_to_xe_device(to_pci_dev(dev));
>  	struct xe_tile *root = xe_device_get_root_tile(xe);
> -	u32 cap;
> +	u32 cap = 0;
>  	int ret;
>  
>  	xe_pm_runtime_get(xe);
> @@ -186,7 +186,7 @@ static void late_bind_remove_files(struct device *dev)
>  {
>  	struct xe_device *xe = pdev_to_xe_device(to_pci_dev(dev));
>  	struct xe_tile *root = xe_device_get_root_tile(xe);
> -	u32 cap;
> +	u32 cap = 0;
>  	int ret;
>  
>  	xe_pm_runtime_get(xe);
> diff --git a/drivers/gpu/drm/xe/xe_hwmon.c b/drivers/gpu/drm/xe/xe_hwmon.c
> index c17ed1ae8649..32a76ae6e9dc 100644
> --- a/drivers/gpu/drm/xe/xe_hwmon.c
> +++ b/drivers/gpu/drm/xe/xe_hwmon.c
> @@ -179,7 +179,7 @@ static int xe_hwmon_pcode_rmw_power_limit(const struct xe_hwmon *hwmon, u32 attr
>  					  u32 clr, u32 set)
>  {
>  	struct xe_tile *root_tile = xe_device_get_root_tile(hwmon->xe);
> -	u32 val0, val1;
> +	u32 val0 = 0, val1 = 0;
>  	int ret = 0;
>  
>  	ret = xe_pcode_read(root_tile, PCODE_MBOX(PCODE_POWER_SETUP,
> @@ -734,7 +734,7 @@ static int xe_hwmon_power_curr_crit_read(struct xe_hwmon *hwmon, int channel,
>  					 long *value, u32 scale_factor)
>  {
>  	int ret;
> -	u32 uval;
> +	u32 uval = 0;
>  
>  	mutex_lock(&hwmon->hwmon_lock);
>  
> @@ -918,7 +918,7 @@ xe_hwmon_power_write(struct xe_hwmon *hwmon, u32 attr, int channel, long val)
>  static umode_t
>  xe_hwmon_curr_is_visible(const struct xe_hwmon *hwmon, u32 attr, int channel)
>  {
> -	u32 uval;
> +	u32 uval = 0;
>  
>  	/* hwmon sysfs attribute of current available only for package */
>  	if (channel != CHANNEL_PKG)
> @@ -1020,7 +1020,7 @@ xe_hwmon_energy_read(struct xe_hwmon *hwmon, u32 attr, int channel, long *val)
>  static umode_t
>  xe_hwmon_fan_is_visible(struct xe_hwmon *hwmon, u32 attr, int channel)
>  {
> -	u32 uval;
> +	u32 uval = 0;
>  
>  	if (!hwmon->xe->info.has_fan_control)
>  		return 0;
> diff --git a/drivers/gpu/drm/xe/xe_vram_freq.c b/drivers/gpu/drm/xe/xe_vram_freq.c
> index b26e26d73dae..17bc84da4cdc 100644
> --- a/drivers/gpu/drm/xe/xe_vram_freq.c
> +++ b/drivers/gpu/drm/xe/xe_vram_freq.c
> @@ -34,7 +34,7 @@ static ssize_t max_freq_show(struct device *dev, struct device_attribute *attr,
>  			     char *buf)
>  {
>  	struct xe_tile *tile = dev_to_tile(dev);
> -	u32 val, mbox;
> +	u32 val = 0, mbox;
>  	int err;
>  
>  	mbox = REG_FIELD_PREP(PCODE_MB_COMMAND, PCODE_FREQUENCY_CONFIG)
> @@ -56,7 +56,7 @@ static ssize_t min_freq_show(struct device *dev, struct device_attribute *attr,
>  			     char *buf)
>  {
>  	struct xe_tile *tile = dev_to_tile(dev);
> -	u32 val, mbox;
> +	u32 val = 0, mbox;
>  	int err;
>  
>  	mbox = REG_FIELD_PREP(PCODE_MB_COMMAND, PCODE_FREQUENCY_CONFIG)
> -- 
> 2.34.1
>