On 2019-08-26 2:05 p.m., 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.
>
> v2: Fix spacing
> v3: Dump dpcd access on MST read/writes
>
> Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>
Reviewed-by: Harry Wentland <harry.wentland@xxxxxxx>
Harry
> Signed-off-by: David Francis <David.Francis@xxxxxxx>
> ---
> drivers/gpu/drm/drm_dp_aux_dev.c | 12 ++----------
> drivers/gpu/drm/drm_dp_helper.c | 30 ++++++++++++++++++++----------
> 2 files changed, 22 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_aux_dev.c b/drivers/gpu/drm/drm_dp_aux_dev.c
> index 0cfb386754c3..418cad4f649a 100644
> --- a/drivers/gpu/drm/drm_dp_aux_dev.c
> +++ b/drivers/gpu/drm/drm_dp_aux_dev.c
> @@ -163,11 +163,7 @@ 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;
> @@ -215,11 +211,7 @@ 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 ffc68d305afe..2cc21eff4cf3 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -30,6 +30,7 @@
> #include <linux/seq_file.h>
>
> #include <drm/drm_dp_helper.h>
> +#include <drm/drm_dp_mst_helper.h>
> #include <drm/drm_print.h>
> #include <drm/drm_vblank.h>
>
> @@ -251,7 +252,7 @@ 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
> @@ -280,13 +281,18 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
> * We just have to do it before any DPCD access and hope that the
> * monitor doesn't power down exactly after the throw away read.
> */
> - ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV, buffer,
> - 1);
> - if (ret != 1)
> - goto out;
> + if (!aux->is_remote) {
> + ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV,
> + buffer, 1);
> + if (ret != 1)
> + goto out;
> + }
>
> - ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer,
> - size);
> + if (aux->is_remote)
> + ret = drm_dp_mst_dpcd_read(aux, offset, buffer, size);
> + else
> + ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset,
> + buffer, size);
>
> out:
> drm_dp_dump_access(aux, DP_AUX_NATIVE_READ, offset, buffer, ret);
> @@ -296,7 +302,7 @@ 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
> @@ -313,8 +319,12 @@ ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
> {
> int ret;
>
> - ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer,
> - size);
> + if (aux->is_remote)
> + ret = drm_dp_mst_dpcd_write(aux, offset, buffer, size);
> + else
> + 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);
> return ret;
> }
>
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