| Message ID | 20241029095411.657616-1-wenst@chromium.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | drm/bridge: it6505: Fix inverted reset polarity | expand |
On Tue, Oct 29, 2024 at 05:54:10PM +0800, Chen-Yu Tsai wrote: > The IT6505 bridge chip has a active low reset line. Since it is a > "reset" and not an "enable" line, the GPIO should be asserted to > put it in reset and deasserted to bring it out of reset during > the power on sequence. > > The polarity was inverted when the driver was first introduced, likely > because the device family that was targeted had an inverting level > shifter on the reset line. > > The MT8186 Corsola devices already have the IT6505 in their device tree, > but the whole display pipeline is actually disabled and won't be enabled > until some remaining issues are sorted out. The other known user is > the MT8183 Kukui / Jacuzzi family; their device trees currently do not > have the IT6505 included. > > Fix the polarity in the driver while there are no actual users. > > Fixes: b5c84a9edcd4 ("drm/bridge: add it6505 driver") > Cc: <stable@vger.kernel.org> > Signed-off-by: Chen-Yu Tsai <wenst@chromium.org> > --- > drivers/gpu/drm/bridge/ite-it6505.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) The datasheet describes the pin as Active LOW, so the change seems to be correct. Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c index 7502a5f81557..df7ecdf0f422 100644 --- a/drivers/gpu/drm/bridge/ite-it6505.c +++ b/drivers/gpu/drm/bridge/ite-it6505.c @@ -2618,9 +2618,9 @@ static int it6505_poweron(struct it6505 *it6505) /* time interval between OVDD and SYSRSTN at least be 10ms */ if (pdata->gpiod_reset) { usleep_range(10000, 20000); - gpiod_set_value_cansleep(pdata->gpiod_reset, 0); - usleep_range(1000, 2000); gpiod_set_value_cansleep(pdata->gpiod_reset, 1); + usleep_range(1000, 2000); + gpiod_set_value_cansleep(pdata->gpiod_reset, 0); usleep_range(25000, 35000); } @@ -2651,7 +2651,7 @@ static int it6505_poweroff(struct it6505 *it6505) disable_irq_nosync(it6505->irq); if (pdata->gpiod_reset) - gpiod_set_value_cansleep(pdata->gpiod_reset, 0); + gpiod_set_value_cansleep(pdata->gpiod_reset, 1); if (pdata->pwr18) { err = regulator_disable(pdata->pwr18); @@ -3205,7 +3205,7 @@ static int it6505_init_pdata(struct it6505 *it6505) return PTR_ERR(pdata->ovdd); } - pdata->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW); + pdata->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH); if (IS_ERR(pdata->gpiod_reset)) { dev_err(dev, "gpiod_reset gpio not found"); return PTR_ERR(pdata->gpiod_reset);
The IT6505 bridge chip has a active low reset line. Since it is a "reset" and not an "enable" line, the GPIO should be asserted to put it in reset and deasserted to bring it out of reset during the power on sequence. The polarity was inverted when the driver was first introduced, likely because the device family that was targeted had an inverting level shifter on the reset line. The MT8186 Corsola devices already have the IT6505 in their device tree, but the whole display pipeline is actually disabled and won't be enabled until some remaining issues are sorted out. The other known user is the MT8183 Kukui / Jacuzzi family; their device trees currently do not have the IT6505 included. Fix the polarity in the driver while there are no actual users. Fixes: b5c84a9edcd4 ("drm/bridge: add it6505 driver") Cc: <stable@vger.kernel.org> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org> --- drivers/gpu/drm/bridge/ite-it6505.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)