| Message ID | 20220311103525.1431890-1-xji@analogixsemi.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] drm/bridge: anx7625: Fix not correct get property counts | expand |
Hi Xin. On Fri, Mar 11, 2022 at 06:35:25PM +0800, Xin Ji wrote: > The property length which returns from "of_get_property", it means array > bytes count if the property has prefix as "/bits/ 8". The driver should > call function "of_property_read_u8_array" to get correct array value. > > Fixes: fd0310b6fe7d ("drm/bridge: anx7625: add MIPI DPI input feature") > Signed-off-by: Xin Ji <xji@analogixsemi.com> > > --- > V1 -> V2: Fix Sam comment, use of_property_read_u8_array to get array > value > --- > drivers/gpu/drm/bridge/analogix/anx7625.c | 8 ++++---- > drivers/gpu/drm/bridge/analogix/anx7625.h | 4 ++-- > 2 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c > index c6a9a02ed762..628cbf769141 100644 > --- a/drivers/gpu/drm/bridge/analogix/anx7625.c > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c > @@ -1598,8 +1598,8 @@ static int anx7625_get_swing_setting(struct device *dev, > num_regs = DP_TX_SWING_REG_CNT; > > pdata->dp_lane0_swing_reg_cnt = num_regs; > - of_property_read_u32_array(dev->of_node, "analogix,lane0-swing", > - pdata->lane0_reg_data, num_regs); > + of_property_read_u8_array(dev->of_node, "analogix,lane0-swing", > + pdata->lane0_reg_data, num_regs); The current implementation do a two step approach. First is find the number of elements and then read the elements. The number of elements is only used to limit what is read. I suggest to use: of_property_read_u8_array(dev->of_node, "analogix,lane0-swing", pdata->lane0_reg_data, DP_TX_SWING_REG_CNT); Then you a guaranteed to read at maximum DP_TX_SWING_REG_CNT entries. And as the number of elements is not stored anywhere that should be fine. This looks simpler and matches what we for example do in drivers/gpu/drm/arm/malidp_drv.c - the only user in gpu/ of of_property_read_u8_array(). Sam
On Fri, Mar 11, 2022 at 12:36:09PM +0100, Sam Ravnborg wrote: > Hi Xin. > > On Fri, Mar 11, 2022 at 06:35:25PM +0800, Xin Ji wrote: > > The property length which returns from "of_get_property", it means array > > bytes count if the property has prefix as "/bits/ 8". The driver should > > call function "of_property_read_u8_array" to get correct array value. > > > > Fixes: fd0310b6fe7d ("drm/bridge: anx7625: add MIPI DPI input feature") > > Signed-off-by: Xin Ji <xji@analogixsemi.com> > > > > --- > > V1 -> V2: Fix Sam comment, use of_property_read_u8_array to get array > > value > > --- > > drivers/gpu/drm/bridge/analogix/anx7625.c | 8 ++++---- > > drivers/gpu/drm/bridge/analogix/anx7625.h | 4 ++-- > > 2 files changed, 6 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c > > index c6a9a02ed762..628cbf769141 100644 > > --- a/drivers/gpu/drm/bridge/analogix/anx7625.c > > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c > > @@ -1598,8 +1598,8 @@ static int anx7625_get_swing_setting(struct device *dev, > > num_regs = DP_TX_SWING_REG_CNT; > > > > pdata->dp_lane0_swing_reg_cnt = num_regs; > > - of_property_read_u32_array(dev->of_node, "analogix,lane0-swing", > > - pdata->lane0_reg_data, num_regs); > > + of_property_read_u8_array(dev->of_node, "analogix,lane0-swing", > > + pdata->lane0_reg_data, num_regs); > > The current implementation do a two step approach. First is find the > number of elements and then read the elements. > The number of elements is only used to limit what is read. > > I suggest to use: > > of_property_read_u8_array(dev->of_node, "analogix,lane0-swing", > pdata->lane0_reg_data, DP_TX_SWING_REG_CNT); > > Then you a guaranteed to read at maximum DP_TX_SWING_REG_CNT entries. > And as the number of elements is not stored anywhere that should be fine. > > This looks simpler and matches what we for example do in > drivers/gpu/drm/arm/malidp_drv.c - the only user in gpu/ of > of_property_read_u8_array(). Hi Sam, the property is variable, so need two steps to approach, first to get the property length, then to read the elements (the property length may between 1 to DP_TX_SWING_REG_CNT). If directly to read the element, I cannot exactly know how many registers need by configred. Thanks, Xin > > > Sam
diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c index c6a9a02ed762..628cbf769141 100644 --- a/drivers/gpu/drm/bridge/analogix/anx7625.c +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c @@ -1598,8 +1598,8 @@ static int anx7625_get_swing_setting(struct device *dev, num_regs = DP_TX_SWING_REG_CNT; pdata->dp_lane0_swing_reg_cnt = num_regs; - of_property_read_u32_array(dev->of_node, "analogix,lane0-swing", - pdata->lane0_reg_data, num_regs); + of_property_read_u8_array(dev->of_node, "analogix,lane0-swing", + pdata->lane0_reg_data, num_regs); } if (of_get_property(dev->of_node, @@ -1608,8 +1608,8 @@ static int anx7625_get_swing_setting(struct device *dev, num_regs = DP_TX_SWING_REG_CNT; pdata->dp_lane1_swing_reg_cnt = num_regs; - of_property_read_u32_array(dev->of_node, "analogix,lane1-swing", - pdata->lane1_reg_data, num_regs); + of_property_read_u8_array(dev->of_node, "analogix,lane1-swing", + pdata->lane1_reg_data, num_regs); } return 0; diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.h b/drivers/gpu/drm/bridge/analogix/anx7625.h index edbbfe410a56..2c340f16f2c3 100644 --- a/drivers/gpu/drm/bridge/analogix/anx7625.h +++ b/drivers/gpu/drm/bridge/analogix/anx7625.h @@ -426,9 +426,9 @@ struct anx7625_platform_data { int mipi_lanes; int audio_en; int dp_lane0_swing_reg_cnt; - int lane0_reg_data[DP_TX_SWING_REG_CNT]; int dp_lane1_swing_reg_cnt; - int lane1_reg_data[DP_TX_SWING_REG_CNT]; + u8 lane0_reg_data[DP_TX_SWING_REG_CNT]; + u8 lane1_reg_data[DP_TX_SWING_REG_CNT]; u32 low_power_mode; struct device_node *mipi_host_node; };
The property length which returns from "of_get_property", it means array bytes count if the property has prefix as "/bits/ 8". The driver should call function "of_property_read_u8_array" to get correct array value. Fixes: fd0310b6fe7d ("drm/bridge: anx7625: add MIPI DPI input feature") Signed-off-by: Xin Ji <xji@analogixsemi.com> --- V1 -> V2: Fix Sam comment, use of_property_read_u8_array to get array value --- drivers/gpu/drm/bridge/analogix/anx7625.c | 8 ++++---- drivers/gpu/drm/bridge/analogix/anx7625.h | 4 ++-- 2 files changed, 6 insertions(+), 6 deletions(-)