Commit 0ea75e23 authored by Sam Tygier's avatar Sam Tygier Committed by Dave Airlie
Browse files

DRM: ignore invalid EDID extensions 



Currently an invalid EDID extension will cause the whole EDID to be considered invalid. Instead just drop the invalid extensions, and return the valid ones. The base block is modified to claim to have the number valid extensions, and the check sum is updated.

For my EIZO S2242W the base block is fine, but the extension block is all zeros. Without this patch I get no X and no VTs.

Signed-off-by: default avatarSam Tygier <samtygier@yahoo.co.uk>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent c5d46b4e

drivers/gpu/drm/drm_edid.c

+20 −6
Original line number Diff line number Diff line
@@ -240,7 +240,7 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter, unsigned char *buf, 
			.addr	= DDC_ADDR,

			.flags	= I2C_M_RD,

			.len	= len,

			.buf	= buf + start,

			.buf	= buf,

		}

	};
@@ -253,7 +253,7 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter, unsigned char *buf, 
static u8 *

drm_do_get_edid(struct drm_connector *connector, struct i2c_adapter *adapter)

{

	int i, j = 0;

	int i, j = 0, valid_extensions = 0;

	u8 *block, *new;



	if ((block = kmalloc(EDID_LENGTH, GFP_KERNEL)) == NULL)
@@ -280,14 +280,28 @@ drm_do_get_edid(struct drm_connector *connector, struct i2c_adapter *adapter) 


	for (j = 1; j <= block[0x7e]; j++) {

		for (i = 0; i < 4; i++) {

			if (drm_do_probe_ddc_edid(adapter, block, j,

						  EDID_LENGTH))

			if (drm_do_probe_ddc_edid(adapter,

				  block + (valid_extensions + 1) * EDID_LENGTH,

				  j, EDID_LENGTH))

				goto out;

			if (drm_edid_block_valid(block + j * EDID_LENGTH))

			if (drm_edid_block_valid(block + (valid_extensions + 1) * EDID_LENGTH)) {

				valid_extensions++;

				break;

			}

		}

		if (i == 4)

			goto carp;

			dev_warn(connector->dev->dev,

			 "%s: Ignoring invalid EDID block %d.\n",

			 drm_get_connector_name(connector), j);

	}



	if (valid_extensions != block[0x7e]) {

		block[EDID_LENGTH-1] += block[0x7e] - valid_extensions;

		block[0x7e] = valid_extensions;

		new = krealloc(block, (valid_extensions + 1) * EDID_LENGTH, GFP_KERNEL);

		if (!new)

			goto out;

		block = new;

	}



	return block;

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