Fetching the EDID from a connected monitor is an automated thing with NXP TDA19988. But on some boards the fetching fails for the first time silently without any indication that an error has occured. More than that, subsequent fetches of the EDID succeed until the monitor(s) are unplugged.

Add a function to validate the read EDID and retry if the block retrieved is not valid.

Signed-off-by: Andrew Jackson Andrew.Jackson@arm.com Signed-off-by: Liviu Dudau Liviu.Dudau@arm.com --- drivers/gpu/drm/i2c/tda998x_drv.c | 36 ++++++++++++++++++++++++++++-------- 1 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c index d476279..025adc0 100644 --- a/drivers/gpu/drm/i2c/tda998x_drv.c +++ b/drivers/gpu/drm/i2c/tda998x_drv.c @@ -1066,11 +1066,36 @@ static int read_edid_block(struct tda998x_priv *priv, uint8_t *buf, int blk) return 0; }

+static int +read_validate_edid_block(struct tda998x_priv *priv, uint8_t *buf, int blk) +{ + bool print_bad_edid = drm_debug & DRM_UT_KMS; + int ret; + int retries = 1; + + do + { + bool print_bad = print_bad_edid && (retries == 0); + + ret = read_edid_block(priv, buf, blk); + /* Fail on I2C error */ + if (ret) + break; + + /* But retry checksum errored blocks */ + if (drm_edid_block_valid(buf, blk, print_bad)) + break; + else + ret = -EINVAL; + } while (retries-- > 0); + + return ret; +} + static uint8_t *do_get_edid(struct tda998x_priv *priv) { int j, valid_extensions = 0; uint8_t *block, *new; - bool print_bad_edid = drm_debug & DRM_UT_KMS;

if ((block = kmalloc(EDID_LENGTH, GFP_KERNEL)) == NULL) return NULL; @@ -1079,10 +1104,7 @@ static uint8_t *do_get_edid(struct tda998x_priv *priv) reg_clear(priv, REG_TX4, TX4_PD_RAM);

/* base block fetch */ - if (read_edid_block(priv, block, 0)) - goto fail; - - if (!drm_edid_block_valid(block, 0, print_bad_edid)) + if (read_validate_edid_block(priv, block, 0)) goto fail;

/* if there's no extensions, we're done */ @@ -1096,10 +1118,8 @@ static uint8_t *do_get_edid(struct tda998x_priv *priv)

for (j = 1; j <= block[0x7e]; j++) { uint8_t *ext_block = block + (valid_extensions + 1) * EDID_LENGTH; - if (read_edid_block(priv, ext_block, j)) - goto fail;

- if (!drm_edid_block_valid(ext_block, j, print_bad_edid)) + if (read_validate_edid_block(priv, ext_block, j)) goto fail;

valid_extensions++;