Re: [PATCH] drm: Try loading builtin EDIDs first

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 04 Oct 2013, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> If the firmware is builtin and userspace is not yet running, we can
> stall the boot process for a minute whilst the firmware loader times
> out probing for a non-existent connector EDID. This is contrary to the
> expectations of providing a builtin EDID!
>
> In the process, we can rearrange the code to make the error handling
> more resilient and prevent gcc warning about unitialised variables along
> the error paths.
>
> v2: Load builtins first, fix gcc second (Jani) and cosmetics (Ville).
> v3: Verify that we do not read beyond the end of the fwdata (Ville)
> v4: Restore the lost parenthesis (Jani)

Thanks, looks good,
Jani.

> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Reviewed-by: Jani Nikula <jani.nikula@linux.intel.com>
> ---
>  drivers/gpu/drm/drm_edid_load.c | 108 ++++++++++++++++++++--------------------
>  1 file changed, 54 insertions(+), 54 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid_load.c b/drivers/gpu/drm/drm_edid_load.c
> index 271b42bbfb72..75f204bbb888 100644
> --- a/drivers/gpu/drm/drm_edid_load.c
> +++ b/drivers/gpu/drm/drm_edid_load.c
> @@ -32,7 +32,7 @@ MODULE_PARM_DESC(edid_firmware, "Do not probe monitor, use specified EDID blob "
>  	"from built-in data or /lib/firmware instead. ");
>  
>  #define GENERIC_EDIDS 5
> -static char *generic_edid_name[GENERIC_EDIDS] = {
> +static const char *generic_edid_name[GENERIC_EDIDS] = {
>  	"edid/1024x768.bin",
>  	"edid/1280x1024.bin",
>  	"edid/1600x1200.bin",
> @@ -40,7 +40,7 @@ static char *generic_edid_name[GENERIC_EDIDS] = {
>  	"edid/1920x1080.bin",
>  };
>  
> -static u8 generic_edid[GENERIC_EDIDS][128] = {
> +static const u8 generic_edid[GENERIC_EDIDS][128] = {
>  	{
>  	0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00,
>  	0x31, 0xd8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
> @@ -133,63 +133,68 @@ static u8 generic_edid[GENERIC_EDIDS][128] = {
>  	},
>  };
>  
> +static int edid_size(const u8 *edid, int data_size)
> +{
> +	if (data_size < EDID_LENGTH)
> +		return 0;
> +
> +	return (edid[0x7e] + 1) * EDID_LENGTH;
> +}
> +
>  static u8 *edid_load(struct drm_connector *connector, const char *name,
>  			const char *connector_name)
>  {
> -	const struct firmware *fw;
> -	struct platform_device *pdev;
> -	u8 *fwdata = NULL, *edid, *new_edid;
> -	int fwsize, expected;
> -	int builtin = 0, err = 0;
> +	const struct firmware *fw = NULL;
> +	const u8 *fwdata;
> +	u8 *edid;
> +	int fwsize, builtin;
>  	int i, valid_extensions = 0;
>  	bool print_bad_edid = !connector->bad_edid_counter || (drm_debug & DRM_UT_KMS);
>  
> -	pdev = platform_device_register_simple(connector_name, -1, NULL, 0);
> -	if (IS_ERR(pdev)) {
> -		DRM_ERROR("Failed to register EDID firmware platform device "
> -		    "for connector \"%s\"\n", connector_name);
> -		err = -EINVAL;
> -		goto out;
> -	}
> -
> -	err = request_firmware(&fw, name, &pdev->dev);
> -	platform_device_unregister(pdev);
> -
> -	if (err) {
> -		i = 0;
> -		while (i < GENERIC_EDIDS && strcmp(name, generic_edid_name[i]))
> -			i++;
> -		if (i < GENERIC_EDIDS) {
> -			err = 0;
> -			builtin = 1;
> +	builtin = 0;
> +	for (i = 0; i < GENERIC_EDIDS; i++) {
> +		if (strcmp(name, generic_edid_name[i]) == 0) {
>  			fwdata = generic_edid[i];
>  			fwsize = sizeof(generic_edid[i]);
> +			builtin = 1;
> +			break;
>  		}
>  	}
> +	if (!builtin) {
> +		struct platform_device *pdev;
> +		int err;
>  
> -	if (err) {
> -		DRM_ERROR("Requesting EDID firmware \"%s\" failed (err=%d)\n",
> -		    name, err);
> -		goto out;
> -	}
> +		pdev = platform_device_register_simple(connector_name, -1, NULL, 0);
> +		if (IS_ERR(pdev)) {
> +			DRM_ERROR("Failed to register EDID firmware platform device "
> +				  "for connector \"%s\"\n", connector_name);
> +			return ERR_CAST(pdev);
> +		}
> +
> +		err = request_firmware(&fw, name, &pdev->dev);
> +		platform_device_unregister(pdev);
> +		if (err) {
> +			DRM_ERROR("Requesting EDID firmware \"%s\" failed (err=%d)\n",
> +				  name, err);
> +			return ERR_PTR(err);
> +		}
>  
> -	if (fwdata == NULL) {
> -		fwdata = (u8 *) fw->data;
> +		fwdata = fw->data;
>  		fwsize = fw->size;
>  	}
>  
> -	expected = (fwdata[0x7e] + 1) * EDID_LENGTH;
> -	if (expected != fwsize) {
> +	if (edid_size(fwdata, fwsize) != fwsize) {
>  		DRM_ERROR("Size of EDID firmware \"%s\" is invalid "
> -		    "(expected %d, got %d)\n", name, expected, (int) fwsize);
> -		err = -EINVAL;
> -		goto relfw_out;
> +			  "(expected %d, got %d)\n", name,
> +			  edid_size(fwdata, fwsize), (int)fwsize);
> +		edid = ERR_PTR(-EINVAL);
> +		goto out;
>  	}
>  
>  	edid = kmemdup(fwdata, fwsize, GFP_KERNEL);
>  	if (edid == NULL) {
> -		err = -ENOMEM;
> -		goto relfw_out;
> +		edid = ERR_PTR(-ENOMEM);
> +		goto out;
>  	}
>  
>  	if (!drm_edid_block_valid(edid, 0, print_bad_edid)) {
> @@ -197,8 +202,8 @@ static u8 *edid_load(struct drm_connector *connector, const char *name,
>  		DRM_ERROR("Base block of EDID firmware \"%s\" is invalid ",
>  		    name);
>  		kfree(edid);
> -		err = -EINVAL;
> -		goto relfw_out;
> +		edid = ERR_PTR(-EINVAL);
> +		goto out;
>  	}
>  
>  	for (i = 1; i <= edid[0x7e]; i++) {
> @@ -210,19 +215,18 @@ static u8 *edid_load(struct drm_connector *connector, const char *name,
>  	}
>  
>  	if (valid_extensions != edid[0x7e]) {
> +		u8 *new_edid;
> +
>  		edid[EDID_LENGTH-1] += edid[0x7e] - valid_extensions;
>  		DRM_INFO("Found %d valid extensions instead of %d in EDID data "
>  		    "\"%s\" for connector \"%s\"\n", valid_extensions,
>  		    edid[0x7e], name, connector_name);
>  		edid[0x7e] = valid_extensions;
> +
>  		new_edid = krealloc(edid, (valid_extensions + 1) * EDID_LENGTH,
> -		    GFP_KERNEL);
> -		if (new_edid == NULL) {
> -			err = -ENOMEM;
> -			kfree(edid);
> -			goto relfw_out;
> -		}
> -		edid = new_edid;
> +				    GFP_KERNEL);
> +		if (new_edid)
> +			edid = new_edid;
>  	}
>  
>  	DRM_INFO("Got %s EDID base block and %d extension%s from "
> @@ -230,13 +234,9 @@ static u8 *edid_load(struct drm_connector *connector, const char *name,
>  	    "external", valid_extensions, valid_extensions == 1 ? "" : "s",
>  	    name, connector_name);
>  
> -relfw_out:
> -	release_firmware(fw);
> -
>  out:
> -	if (err)
> -		return ERR_PTR(err);
> -
> +	if (fw)
> +		release_firmware(fw);
>  	return edid;
>  }
>  
> -- 
> 1.8.4.rc3
>

-- 
Jani Nikula, Intel Open Source Technology Center
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