commit 3587c856675c45809010c2cee5b21096f6e8e938 upstream. I've found that by just turning the chip on and off via the POWER_DOWN register, I end up getting i2c_transfer errors on HiKey. Investigating further, it turns out that some of the register state in hardware is getting lost, as the device registers are reset when the chip is powered down. Thus this patch simply re-writes the i2c address to the ADV7511_REG_EDID_I2C_ADDR register to ensure its properly set before we try to read the EDID data. Cc: David Airlie <airlied@xxxxxxxx> Cc: Archit Taneja <architt@xxxxxxxxxxxxxx> Cc: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx> Cc: Lars-Peter Clausen <lars@xxxxxxxxxx> Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> Tested-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> Signed-off-by: Archit Taneja <architt@xxxxxxxxxxxxxx> Signed-off-by: Thong Ho <thong.ho.px@xxxxxxxxxxxxxxx> Signed-off-by: Nhan Nguyen <nhan.nguyen.yb@xxxxxxxxxxx> Link: http://patchwork.freedesktop.org/patch/msgid/1484614372-15342-7-git-send-email-john.stultz@xxxxxxxxxx --- drivers/gpu/drm/i2c/adv7511.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i2c/adv7511.c b/drivers/gpu/drm/i2c/adv7511.c index ebb0fc8..dba5c0e 100644 --- a/drivers/gpu/drm/i2c/adv7511.c +++ b/drivers/gpu/drm/i2c/adv7511.c @@ -51,6 +51,10 @@ struct adv7511 { struct gpio_desc *gpio_pd; }; +static const int edid_i2c_addr = 0x7e; +static const int packet_i2c_addr = 0x70; +static const int cec_i2c_addr = 0x78; + static struct adv7511 *encoder_to_adv7511(struct drm_encoder *encoder) { return to_encoder_slave(encoder)->slave_priv; @@ -606,6 +610,9 @@ static int adv7511_get_modes(struct drm_encoder *encoder, ADV7511_INT1_DDC_ERROR); } adv7511->current_edid_segment = -1; + /* Reset the EDID_I2C_ADDR register as it might be cleared */ + regmap_write(adv7511->regmap, ADV7511_REG_EDID_I2C_ADDR, + edid_i2c_addr); } edid = drm_do_get_edid(connector, adv7511_get_edid_block, adv7511); @@ -881,10 +888,6 @@ static int adv7511_parse_dt(struct device_node *np, return 0; } -static const int edid_i2c_addr = 0x7e; -static const int packet_i2c_addr = 0x70; -static const int cec_i2c_addr = 0x78; - static int adv7511_probe(struct i2c_client *i2c, const struct i2c_device_id *id) { struct adv7511_link_config link_config; -- 1.9.1