From mboxrd@z Thu Jan 1 00:00:00 1970 From: john@metanate.com (John Keeping) Date: Thu, 16 Feb 2017 14:11:04 +0000 Subject: [PATCH v3 23/24] drm/rockchip: dw-mipi-dsi: add reset control In-Reply-To: <58A50A91.6010202@rock-chips.com> References: <20170129132444.25251-1-john@metanate.com> <20170129132444.25251-24-john@metanate.com> <58A3CD45.9090309@rock-chips.com> <20170215123944.798ae363.john@metanate.com> <58A50A91.6010202@rock-chips.com> Message-ID: <20170216141104.5ecca1df.john@metanate.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, 16 Feb 2017 10:12:33 +0800, Chris Zhong wrote: > On 02/15/2017 08:39 PM, John Keeping wrote: > > On Wed, 15 Feb 2017 11:38:45 +0800, Chris Zhong wrote: > > > >> On 01/29/2017 09:24 PM, John Keeping wrote: > >>> In order to fully reset the state of the MIPI controller we must assert > >>> this reset. > >>> > >>> This is slightly more complicated than it could be in order to maintain > >>> compatibility with device trees that do not specify the reset property. > >>> > >>> Signed-off-by: John Keeping > >>> Reviewed-by: Chris Zhong > >>> --- > >>> v3: > >>> - Add Chris' Reviewed-by > >>> Unchanged in v2 > >>> > >>> drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 30 ++++++++++++++++++++++++++++++ > >>> 1 file changed, 30 insertions(+) > >>> > >>> diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c > >>> index 58cb8ace2fe8..cf3ca6b0cbdb 100644 > >>> --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c > >>> +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c > >>> @@ -13,6 +13,7 @@ > >>> #include > >>> #include > >>> #include > >>> +#include > >>> #include > >>> #include > >>> #include > >>> @@ -1124,6 +1125,7 @@ static int dw_mipi_dsi_bind(struct device *dev, struct device *master, > >>> of_match_device(dw_mipi_dsi_dt_ids, dev); > >>> const struct dw_mipi_dsi_plat_data *pdata = of_id->data; > >>> struct platform_device *pdev = to_platform_device(dev); > >>> + struct reset_control *apb_rst; > >>> struct drm_device *drm = data; > >>> struct dw_mipi_dsi *dsi; > >>> struct resource *res; > >>> @@ -1162,6 +1164,34 @@ static int dw_mipi_dsi_bind(struct device *dev, struct device *master, > >>> return ret; > >>> } > >>> > >>> + /* > >>> + * Note that the reset was not defined in the initial device tree, so > >>> + * we have to be prepared for it not being found. > >>> + */ > >>> + apb_rst = devm_reset_control_get(dev, "apb"); > >>> + if (IS_ERR(apb_rst)) { > >>> + if (PTR_ERR(apb_rst) == -ENODEV) { > >> According to [0], I think it should be -ENOENT here. > > Nice catch, I'll fix this. > > > >> [0] > >> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=3d81216fde465e76c5eae98f61d3666163634395 > >> > >> commit 3d81216fde465e76c5eae98f61d3666163634395 > >> Author: Alban Bedel > >> Date: Tue Sep 1 17:28:31 2015 +0200 > >> > >> reset: Fix of_reset_control_get() for consistent return values > >> > >> When of_reset_control_get() is called without connection ID it returns > >> -ENOENT when the 'resets' property doesn't exists or is an empty entry. > >> However when a connection ID is given it returns -EINVAL when the > >> 'resets' > >> property doesn't exists or the requested name can't be found. This is > >> because the error code returned by of_property_match_string() is just > >> passed down as an index to of_parse_phandle_with_args(), which then > >> returns -EINVAL. > >> > >> To get a consistent return value with both code paths we must return > >> -ENOENT when of_property_match_string() fails. > >> > >> Signed-off-by: Alban Bedel > >> Signed-off-by: Philipp Zabel > >> > >> > >>> + apb_rst = NULL; > >>> + } else { > >>> + dev_err(dev, "Unable to get reset control: %d\n", ret); > Also, we can not get error number from "ret" here. Good point, I'll fix this. John