Re: [PATCH v4 05/11] drm: Helper to read max bits per component

On Mon, Jun 06, 2016 at 04:29:07PM +0300, Mika Kahola wrote:

Helper routine to read out maximum supported bits per component for DisplayPort legay converters.

Signed-off-by: Mika Kahola mika.kahola@intel.com

drivers/gpu/drm/drm_dp_helper.c | 31 +++++++++++++++++++++++++++++++ include/drm/drm_dp_helper.h | 2 ++ 2 files changed, 33 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 18b72eb..bac0ccc 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -507,6 +507,37 @@ int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE], } EXPORT_SYMBOL(drm_dp_downstream_max_clock);

+/**

• • drm_dp_downstream_max_bpc() - extract branch device max

• •                           bits per component
    

• • @dpcd: DisplayPort configuration data
• • @port_cap: port capabilities
• • Returns max bpc on success or negative error code on failure
• */

+int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],

•                          const u8 port_cap[4])
  

+{

• int type = drm_dp_downstream_type(dpcd, port_cap);
• bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &

• DP_DETAILED_CAP_INFO_AVAILABLE;
  

• if (detailed_cap_info) {

Early return again.

• if (type != DP_DS_PORT_TYPE_WIRELESS) {
  

switch() again.

• 	int tmp;
  

• 	tmp = port_cap[2] & DP_DS_VGA_MAX_BPC_MASK;
  

Should drop the "VGA" from that stuff since it applies to more than that.

• 	if (tmp == 0)
  

• 		return 8;
  

• 	else
  

• 		return 8 + (1<<tmp);
  

switch() with each case would be less magicy.

• }
  

• }
• return -EINVAL;

Again I think I'd just use 0 here.

+} +EXPORT_SYMBOL(drm_dp_downstream_max_bpc);

/*

• I2C-over-AUX implementation

*/ diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index c3324d3..d4abc38 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -812,6 +812,8 @@ int drm_dp_downstream_port_cap(struct drm_dp_aux *aux, int drm_dp_downstream_type(const u8 dpcd[DP_RECEIVER_CAP_SIZE], const u8 port_cap[4]); int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE], const u8 port_cap[4]); +int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],

•                          const u8 port_cap[4]);
  
  

int drm_dp_aux_register(struct drm_dp_aux *aux); void drm_dp_aux_unregister(struct drm_dp_aux *aux); -- 1.9.1