[PATCH 1/2] drm/dp: Export drm_dp_dpcd_access()

[Imre Deak]

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 at lists.freedesktop.org
Signed-off-by: Imre Deak <imre.deak at 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,
-- 
2.30.2