From: Xin Ji <xji@analogixsemi.com> To: Sam Ravnborg <sam@ravnborg.org> Cc: Andrzej Hajda <andrzej.hajda@intel.com>, Neil Armstrong <narmstrong@baylibre.com>, Robert Foss <robert.foss@linaro.org>, Laurent Pinchart <Laurent.pinchart@ideasonboard.com>, Jonas Karlman <jonas@kwiboo.se>, Jernej Skrabec <jernej.skrabec@gmail.com>, David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>, qwen@analogixsemi.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, mliu@analogixsemi.com, hsinyi@chromium.org, bliang@analogixsemi.com Subject: Re: [PATCH v2] drm/bridge: anx7625: Fix not correct get property counts Date: Mon, 14 Mar 2022 14:04:11 +0800 [thread overview] Message-ID: <20220314060411.GA1456403@anxtwsw-Precision-3640-Tower> (raw) In-Reply-To: <Yis0KXVqZokrkoP7@ravnborg.org> 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
WARNING: multiple messages have this Message-ID (diff)
From: Xin Ji <xji@analogixsemi.com> To: Sam Ravnborg <sam@ravnborg.org> Cc: dri-devel@lists.freedesktop.org, Jonas Karlman <jonas@kwiboo.se>, David Airlie <airlied@linux.ie>, Robert Foss <robert.foss@linaro.org>, qwen@analogixsemi.com, Neil Armstrong <narmstrong@baylibre.com>, linux-kernel@vger.kernel.org, Jernej Skrabec <jernej.skrabec@gmail.com>, mliu@analogixsemi.com, Laurent Pinchart <Laurent.pinchart@ideasonboard.com>, Andrzej Hajda <andrzej.hajda@intel.com>, hsinyi@chromium.org, bliang@analogixsemi.com Subject: Re: [PATCH v2] drm/bridge: anx7625: Fix not correct get property counts Date: Mon, 14 Mar 2022 14:04:11 +0800 [thread overview] Message-ID: <20220314060411.GA1456403@anxtwsw-Precision-3640-Tower> (raw) In-Reply-To: <Yis0KXVqZokrkoP7@ravnborg.org> 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
next prev parent reply other threads:[~2022-03-14 6:04 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-03-11 10:35 [PATCH v2] drm/bridge: anx7625: Fix not correct get property counts Xin Ji 2022-03-11 10:35 ` Xin Ji 2022-03-11 11:36 ` Sam Ravnborg 2022-03-11 11:36 ` Sam Ravnborg 2022-03-14 6:04 ` Xin Ji [this message] 2022-03-14 6:04 ` Xin Ji
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