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 seems some of the register state in the regmap cache is somehow getting lost. Using the logic in __adv7511_power_on/off() which syncs and dirtys the cache avoids this issue. Thus this patch changes the EDID probing logic so that we re-use the __adv7511_power_on/off() calls. Cc: David Airlie <airl...@linux.ie> Cc: Archit Taneja <arch...@codeaurora.org> Cc: Wolfram Sang <wsa+rene...@sang-engineering.com> Cc: Lars-Peter Clausen <l...@metafoo.de> Cc: Laurent Pinchart <laurent.pinch...@ideasonboard.com> Cc: dri-de...@lists.freedesktop.org Signed-off-by: John Stultz <john.stu...@linaro.org> --- v2: Split into two patches to make the change more clear. Also provided more rational as to why the change is important. drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-) diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c index 1948968..487b33d 100644 --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c @@ -559,24 +559,13 @@ static int adv7511_get_modes(struct adv7511 *adv7511, unsigned int count; /* Reading the EDID only works if the device is powered */ - if (!adv7511->powered) { - regmap_update_bits(adv7511->regmap, ADV7511_REG_POWER, - ADV7511_POWER_POWER_DOWN, 0); - if (adv7511->i2c_main->irq) { - regmap_write(adv7511->regmap, ADV7511_REG_INT_ENABLE(0), - ADV7511_INT0_EDID_READY); - regmap_write(adv7511->regmap, ADV7511_REG_INT_ENABLE(1), - ADV7511_INT1_DDC_ERROR); - } - adv7511->current_edid_segment = -1; - } + if (!adv7511->powered) + __adv7511_power_on(adv7511); edid = drm_do_get_edid(connector, adv7511_get_edid_block, adv7511); if (!adv7511->powered) - regmap_update_bits(adv7511->regmap, ADV7511_REG_POWER, - ADV7511_POWER_POWER_DOWN, - ADV7511_POWER_POWER_DOWN); + __adv7511_power_off(adv7511); kfree(adv7511->edid); adv7511->edid = edid; -- 2.7.4