Re: [PATCH libdrm 1/2] xf86drm: fallback to MODALIAS for OF less platform devices

[Eric Engestrom <eric.engestrom@intel.com>]

On Wednesday, 2019-01-23 10:45:17 +0000, Emil Velikov wrote:
> From: Emil Velikov <emil.velikov@collabora.com>
> 
> Some devices can lack OF data or it may not be available in the uevent
> file. Fallback to the MODALIAS data in those cases.
> 
> We strip any leading "MODALIAS=.*:" thus the resulting information is
> compatible with existing code in Mesa.
> 
> Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
> ---
>  xf86drm.c | 55 ++++++++++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 42 insertions(+), 13 deletions(-)
> 
> diff --git a/xf86drm.c b/xf86drm.c
> index 10df682b..374734eb 100644
> --- a/xf86drm.c
> +++ b/xf86drm.c
> @@ -3511,15 +3511,28 @@ free_device:
>  static int drmParsePlatformBusInfo(int maj, int min, drmPlatformBusInfoPtr info)
>  {
>  #ifdef __linux__
> -    char path[PATH_MAX + 1], *name;
> +    char path[PATH_MAX + 1], *name, *foo;

I assume you didn't mean to send this patch yet? :P

>  
>      snprintf(path, sizeof(path), "/sys/dev/char/%d:%d/device", maj, min);
>  
>      name = sysfs_uevent_get(path, "OF_FULLNAME");
> -    if (!name)
> -        return -ENOENT;
> +    foo = name;
> +    if (!name) {
> +        /* If the device lacks OF data, pick the MODALIAS info */
> +        name = sysfs_uevent_get(path, "MODALIAS");
> +        if (!name)
> +            return -ENOENT;
> +
> +        /* .. and strip the MODALIAS=[platform,usb...]: part. */
> +        foo = strrchr(name, ':');
> +        if (!foo) {
> +            free(name);
> +            return -ENOENT;
> +        }
> +        foo++;
> +    }
>  
> -    strncpy(info->fullname, name, DRM_PLATFORM_DEVICE_NAME_LEN);
> +    strncpy(info->fullname, foo, DRM_PLATFORM_DEVICE_NAME_LEN);
>      info->fullname[DRM_PLATFORM_DEVICE_NAME_LEN - 1] = '\0';
>      free(name);
>  
> @@ -3534,18 +3547,20 @@ static int drmParsePlatformDeviceInfo(int maj, int min,
>                                        drmPlatformDeviceInfoPtr info)
>  {
>  #ifdef __linux__
> -    char path[PATH_MAX + 1], *value;
> +    char path[PATH_MAX + 1], *value, *foo;
>      unsigned int count, i;
>      int err;
>  
>      snprintf(path, sizeof(path), "/sys/dev/char/%d:%d/device", maj, min);
>  
>      value = sysfs_uevent_get(path, "OF_COMPATIBLE_N");
> -    if (!value)
> -        return -ENOENT;
> -
> -    sscanf(value, "%u", &count);
> -    free(value);
> +    if (value) {
> +        sscanf(value, "%u", &count);
> +        free(value);
> +    } else {
> +        /* Assume one entry if the device lack OF data */
> +        count = 1;
> +    }
>  
>      info->compatible = calloc(count + 1, sizeof(*info->compatible));
>      if (!info->compatible)
> @@ -3553,12 +3568,26 @@ static int drmParsePlatformDeviceInfo(int maj, int min,
>  
>      for (i = 0; i < count; i++) {
>          value = sysfs_uevent_get(path, "OF_COMPATIBLE_%u", i);
> +        foo = value;
>          if (!value) {
> -            err = -ENOENT;
> -            goto free;
> +            /* If the device lacks OF data, pick the MODALIAS info */
> +            value = sysfs_uevent_get(path, "MODALIAS");
> +            if (!value) {
> +                err = -ENOENT;
> +                goto free;
> +            }
> +
> +            /* .. and strip the MODALIAS=[platform,usb...]: part. */
> +            foo = strrchr(value, ':');
> +            if (!foo) {
> +                free(value);
> +                return -ENOENT;
> +            }
> +            foo = strdup(foo + 1);
> +            free(value);
>          }
>  
> -        info->compatible[i] = value;
> +        info->compatible[i] = foo;
>      }
>  
>      return 0;
> -- 
> 2.20.1
> 
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