| Message ID | 20220407183826.724106-1-imre.deak@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] drm/dp: Export drm_dp_dpcd_access() | expand |
On Thu, 07 Apr 2022, Imre Deak <imre.deak@intel.com> wrote: > The next patch needs a way to read a DPCD register without the preceding > wake-up read in drm_dp_dpcd_read(). Export drm_dp_dpcd_access() to allow > this. I think I'd rather you added a special "probe" function for this specific purpose. I think drm_dp_dpcd_access() is a too generic low level function to export, and runs the risk of complicating any potential future refactoring of the DP AUX code. Something like this: ssize_t drm_dp_dpcd_probe(struct drm_dp_aux *aux, unsigned int offset); And you could reuse that for the wakeup in drm_dp_dpcd_read() too. BR, Jani. > > Cc: dri-devel@lists.freedesktop.org > Signed-off-by: Imre Deak <imre.deak@intel.com> > --- > drivers/gpu/drm/dp/drm_dp.c | 19 +++++++++++++++++-- > include/drm/dp/drm_dp_helper.h | 2 ++ > 2 files changed, 19 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/dp/drm_dp.c b/drivers/gpu/drm/dp/drm_dp.c > index 580016a1b9eb7..8b181314edcbe 100644 > --- a/drivers/gpu/drm/dp/drm_dp.c > +++ b/drivers/gpu/drm/dp/drm_dp.c > @@ -470,8 +470,22 @@ drm_dp_dump_access(const struct drm_dp_aux *aux, > * Both native and I2C-over-AUX transactions are supported. > */ > > -static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, > - unsigned int offset, void *buffer, size_t size) > +/** > + * drm_dp_dpcd_access() - read or write a series of bytes from/to the DPCD > + * @aux: DisplayPort AUX channel (SST) > + * @request: DP_AUX_NATIVE_READ or DP_AUX_NATIVE_WRITE > + * @offset: address of the (first) register to read or write > + * @buffer: buffer with the register values to write or the register values read > + * @size: number of bytes in @buffer > + * > + * Returns the number of bytes transferred on success, or a negative error > + * code on failure. This is a low-level function only for SST sinks and cases > + * where calling drm_dp_dpcd_read()/write() is not possible (for instance due > + * to the wake-up register read in drm_dp_dpcd_read()). For all other cases > + * the latter functions should be used. > + */ > +int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, > + unsigned int offset, void *buffer, size_t size) > { > struct drm_dp_aux_msg msg; > unsigned int retry, native_reply; > @@ -526,6 +540,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, > mutex_unlock(&aux->hw_mutex); > return ret; > } > +EXPORT_SYMBOL(drm_dp_dpcd_access); > > /** > * drm_dp_dpcd_read() - read a series of bytes from the DPCD > diff --git a/include/drm/dp/drm_dp_helper.h b/include/drm/dp/drm_dp_helper.h > index 1eccd97419436..7cf6e83434a8c 100644 > --- a/include/drm/dp/drm_dp_helper.h > +++ b/include/drm/dp/drm_dp_helper.h > @@ -2053,6 +2053,8 @@ struct drm_dp_aux { > bool is_remote; > }; > > +int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, > + unsigned int offset, void *buffer, size_t size); > ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, > void *buffer, size_t size); > ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
On Thu, Apr 07, 2022 at 10:32:11PM +0300, Jani Nikula wrote: > On Thu, 07 Apr 2022, Imre Deak <imre.deak@intel.com> wrote: > > The next patch needs a way to read a DPCD register without the preceding > > wake-up read in drm_dp_dpcd_read(). Export drm_dp_dpcd_access() to allow > > this. > > I think I'd rather you added a special "probe" function for this > specific purpose. I think drm_dp_dpcd_access() is a too generic low > level function to export, and runs the risk of complicating any > potential future refactoring of the DP AUX code. > > Something like this: > > ssize_t drm_dp_dpcd_probe(struct drm_dp_aux *aux, unsigned int offset); > > And you could reuse that for the wakeup in drm_dp_dpcd_read() too. Ok, makes sense, I'll change that. > BR, > Jani. > > > > > Cc: dri-devel@lists.freedesktop.org > > Signed-off-by: Imre Deak <imre.deak@intel.com> > > --- > > drivers/gpu/drm/dp/drm_dp.c | 19 +++++++++++++++++-- > > include/drm/dp/drm_dp_helper.h | 2 ++ > > 2 files changed, 19 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/dp/drm_dp.c b/drivers/gpu/drm/dp/drm_dp.c > > index 580016a1b9eb7..8b181314edcbe 100644 > > --- a/drivers/gpu/drm/dp/drm_dp.c > > +++ b/drivers/gpu/drm/dp/drm_dp.c > > @@ -470,8 +470,22 @@ drm_dp_dump_access(const struct drm_dp_aux *aux, > > * Both native and I2C-over-AUX transactions are supported. > > */ > > > > -static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, > > - unsigned int offset, void *buffer, size_t size) > > +/** > > + * drm_dp_dpcd_access() - read or write a series of bytes from/to the DPCD > > + * @aux: DisplayPort AUX channel (SST) > > + * @request: DP_AUX_NATIVE_READ or DP_AUX_NATIVE_WRITE > > + * @offset: address of the (first) register to read or write > > + * @buffer: buffer with the register values to write or the register values read > > + * @size: number of bytes in @buffer > > + * > > + * Returns the number of bytes transferred on success, or a negative error > > + * code on failure. This is a low-level function only for SST sinks and cases > > + * where calling drm_dp_dpcd_read()/write() is not possible (for instance due > > + * to the wake-up register read in drm_dp_dpcd_read()). For all other cases > > + * the latter functions should be used. > > + */ > > +int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, > > + unsigned int offset, void *buffer, size_t size) > > { > > struct drm_dp_aux_msg msg; > > unsigned int retry, native_reply; > > @@ -526,6 +540,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, > > mutex_unlock(&aux->hw_mutex); > > return ret; > > } > > +EXPORT_SYMBOL(drm_dp_dpcd_access); > > > > /** > > * drm_dp_dpcd_read() - read a series of bytes from the DPCD > > diff --git a/include/drm/dp/drm_dp_helper.h b/include/drm/dp/drm_dp_helper.h > > index 1eccd97419436..7cf6e83434a8c 100644 > > --- a/include/drm/dp/drm_dp_helper.h > > +++ b/include/drm/dp/drm_dp_helper.h > > @@ -2053,6 +2053,8 @@ struct drm_dp_aux { > > bool is_remote; > > }; > > > > +int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, > > + unsigned int offset, void *buffer, size_t size); > > ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, > > void *buffer, size_t size); > > ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset, > > -- > Jani Nikula, Intel Open Source Graphics Center
diff --git a/drivers/gpu/drm/dp/drm_dp.c b/drivers/gpu/drm/dp/drm_dp.c index 580016a1b9eb7..8b181314edcbe 100644 --- a/drivers/gpu/drm/dp/drm_dp.c +++ b/drivers/gpu/drm/dp/drm_dp.c @@ -470,8 +470,22 @@ drm_dp_dump_access(const struct drm_dp_aux *aux, * Both native and I2C-over-AUX transactions are supported. */ -static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, - unsigned int offset, void *buffer, size_t size) +/** + * drm_dp_dpcd_access() - read or write a series of bytes from/to the DPCD + * @aux: DisplayPort AUX channel (SST) + * @request: DP_AUX_NATIVE_READ or DP_AUX_NATIVE_WRITE + * @offset: address of the (first) register to read or write + * @buffer: buffer with the register values to write or the register values read + * @size: number of bytes in @buffer + * + * Returns the number of bytes transferred on success, or a negative error + * code on failure. This is a low-level function only for SST sinks and cases + * where calling drm_dp_dpcd_read()/write() is not possible (for instance due + * to the wake-up register read in drm_dp_dpcd_read()). For all other cases + * the latter functions should be used. + */ +int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, + unsigned int offset, void *buffer, size_t size) { struct drm_dp_aux_msg msg; unsigned int retry, native_reply; @@ -526,6 +540,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, mutex_unlock(&aux->hw_mutex); return ret; } +EXPORT_SYMBOL(drm_dp_dpcd_access); /** * drm_dp_dpcd_read() - read a series of bytes from the DPCD diff --git a/include/drm/dp/drm_dp_helper.h b/include/drm/dp/drm_dp_helper.h index 1eccd97419436..7cf6e83434a8c 100644 --- a/include/drm/dp/drm_dp_helper.h +++ b/include/drm/dp/drm_dp_helper.h @@ -2053,6 +2053,8 @@ struct drm_dp_aux { bool is_remote; }; +int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, + unsigned int offset, void *buffer, size_t size); ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, void *buffer, size_t size); ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
The next patch needs a way to read a DPCD register without the preceding wake-up read in drm_dp_dpcd_read(). Export drm_dp_dpcd_access() to allow this. Cc: dri-devel@lists.freedesktop.org Signed-off-by: Imre Deak <imre.deak@intel.com> --- drivers/gpu/drm/dp/drm_dp.c | 19 +++++++++++++++++-- include/drm/dp/drm_dp_helper.h | 2 ++ 2 files changed, 19 insertions(+), 2 deletions(-)