Re: [PATCH v3 10/16] drm/dp-mst: Add MST support to DP DPCD R/W functions

On Wed, 2019-08-21 at 16:01 -0400, David Francis wrote:

Instead of having drm_dp_dpcd_read/write and drm_dp_mst_dpcd_read/write as entry points into the aux code, have drm_dp_dpcd_read/write handle both.

This means that DRM drivers can make MST DPCD read/writes.

Cc: Leo Li sunpeng.li@amd.com Cc: Lyude Paul lyude@redhat.com Signed-off-by: David Francis David.Francis@amd.com

---

drivers/gpu/drm/drm_dp_aux_dev.c | 12 ++---------- drivers/gpu/drm/drm_dp_helper.c | 10 ++++++++-- 2 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_aux_dev.c b/drivers/gpu/drm/drm_dp_aux_dev.c index 00610bd8d6c1..0780fc358389 100644 --- a/drivers/gpu/drm/drm_dp_aux_dev.c +++ b/drivers/gpu/drm/drm_dp_aux_dev.c @@ -162,11 +162,7 @@ static ssize_t auxdev_read_iter(struct kiocb *iocb, struct iov_iter *to) break; }

• if (aux_dev->aux->is_remote)
  

• 	res = drm_dp_mst_dpcd_read(aux_dev->aux, pos, buf,
  

• 				   todo);
  

• else
  

• 	res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);
  

• res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);
  
  

  if (res <= 0) break;

@@ -214,11 +210,7 @@ static ssize_t auxdev_write_iter(struct kiocb *iocb, struct iov_iter *from) break; }

• if (aux_dev->aux->is_remote)
  

• 	res = drm_dp_mst_dpcd_write(aux_dev->aux, pos, buf,
  

• 				    todo);
  

• else
  

• 	res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);
  

• res = drm_dp_mst_dpcd_write(aux_dev->aux, pos, buf, todo);
  
  

  if (res <= 0) break;

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 54a6414c5d96..9f976b90c53a 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -29,6 +29,7 @@ #include <linux/i2c.h> #include <linux/seq_file.h> #include <drm/drm_dp_helper.h> +#include <drm/drm_dp_mst_helper.h> #include <drm/drmP.h>

#include "drm_crtc_helper_internal.h" @@ -272,7 +273,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,

/**

• drm_dp_dpcd_read() - read a series of bytes from the DPCD

• • @aux: DisplayPort AUX channel

• • @aux: DisplayPort AUX channel (SST or MST)
  • @offset: address of the (first) register to read
  • @buffer: buffer to store the register values
  • @size: number of bytes in @buffer

@@ -289,6 +290,8 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, { int ret;

•    if (aux->is_remote)
  

•            return drm_dp_mst_dpcd_read(aux, offset, buffer, size);
  

Please follow the kernel style guidelines. We indent with tabs first, not spaces.

/* * HP ZR24w corrupts the first DPCD access after entering power save * mode. Eg. on a read, the entire buffer will be filled with the same @@ -317,7 +320,7 @@ EXPORT_SYMBOL(drm_dp_dpcd_read);

/**

• drm_dp_dpcd_write() - write a series of bytes to the DPCD

• • @aux: DisplayPort AUX channel

• • @aux: DisplayPort AUX channel (SST or MST)
  • @offset: address of the (first) register to write
  • @buffer: buffer containing the values to write
  • @size: number of bytes in @buffer

@@ -334,6 +337,9 @@ ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset, { int ret;

•    if (aux->is_remote)
  

•            return drm_dp_mst_dpcd_write(aux, offset, buffer, size);
  

Same here

ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer, size); drm_dp_dump_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer, ret);