linux-kernel - Re: [PATCH v3 3/5] drm/dp: make dp_link_status and dp_get_lane

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Date:   Thu, 13 Sep 2018 13:20:30 +0200
From:   Andrzej Hajda <a.hajda@...sung.com>
To:     Damian Kos <dkos@...ence.com>, David Airlie <airlied@...ux.ie>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Archit Taneja <architt@...eaurora.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Gustavo Padovan <gustavo@...ovan.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Sean Paul <sean@...rly.run>, Sandy Huang <hjc@...k-chips.com>,
        Heiko Stübner <heiko@...ech.de>,
        Quentin Schulz <quentin.schulz@...tlin.com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org
Cc:     pgaj@...ence.com, ltyrala@...ence.com, stelford@...ence.com,
        jartur@...ence.com, piotrs@...ence.com
Subject: Re: [PATCH v3 3/5] drm/dp: make dp_link_status and
 dp_get_lane_status usable from outside of the core

On 28.08.2018 12:24, Damian Kos wrote:
> From: Quentin Schulz <quentin.schulz@...tlin.com>
>
> dp_link_status and dp_get_lane_status are pretty generic and can be used for
> other means, so let's make it "public".
>
> This adds drm_dp_link_status and drm_dp_get_lane_status to the header file and
> add the appropriate EXPORT_SYMBOL for it so that it can be used by other
> drivers, be they compiled built-in or as modules.

If you want to export them please document functions and their arguments.
Moreover, these functions are so tiny, so they can be defined as inline.


>
> Signed-off-by: Damian Kos <dkos@...ence.com>
No author sign-off.

Regards
Andrzej


> ---
>  drivers/gpu/drm/drm_dp_helper.c | 20 +++++++++++---------
>  include/drm/drm_dp_helper.h     |  3 +++
>  2 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 4b5bf6ee7fa7..ee9ec2ccf878 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -43,19 +43,21 @@
>   */
>  
>  /* Helpers for DP link training */
> -static u8 dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r)
> +u8 drm_dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r)
>  {
>  	return link_status[r - DP_LANE0_1_STATUS];
>  }
> +EXPORT_SYMBOL(drm_dp_link_status);
>  
> -static u8 dp_get_lane_status(const u8 link_status[DP_LINK_STATUS_SIZE],
> +u8 drm_dp_get_lane_status(const u8 link_status[DP_LINK_STATUS_SIZE],
>  			     int lane)
>  {
>  	int i = DP_LANE0_1_STATUS + (lane >> 1);
>  	int s = (lane & 1) * 4;
> -	u8 l = dp_link_status(link_status, i);
> +	u8 l = drm_dp_link_status(link_status, i);
>  	return (l >> s) & 0xf;
>  }
> +EXPORT_SYMBOL(drm_dp_get_lane_status);
>  
>  bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
>  			  int lane_count)
> @@ -64,12 +66,12 @@ bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
>  	u8 lane_status;
>  	int lane;
>  
> -	lane_align = dp_link_status(link_status,
> -				    DP_LANE_ALIGN_STATUS_UPDATED);
> +	lane_align = drm_dp_link_status(link_status,
> +					DP_LANE_ALIGN_STATUS_UPDATED);
>  	if ((lane_align & DP_INTERLANE_ALIGN_DONE) == 0)
>  		return false;
>  	for (lane = 0; lane < lane_count; lane++) {
> -		lane_status = dp_get_lane_status(link_status, lane);
> +		lane_status = drm_dp_get_lane_status(link_status, lane);
>  		if ((lane_status & DP_CHANNEL_EQ_BITS) != DP_CHANNEL_EQ_BITS)
>  			return false;
>  	}
> @@ -84,7 +86,7 @@ bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
>  	u8 lane_status;
>  
>  	for (lane = 0; lane < lane_count; lane++) {
> -		lane_status = dp_get_lane_status(link_status, lane);
> +		lane_status = drm_dp_get_lane_status(link_status, lane);
>  		if ((lane_status & DP_LANE_CR_DONE) == 0)
>  			return false;
>  	}
> @@ -99,7 +101,7 @@ u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE],
>  	int s = ((lane & 1) ?
>  		 DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT :
>  		 DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT);
> -	u8 l = dp_link_status(link_status, i);
> +	u8 l = drm_dp_link_status(link_status, i);
>  
>  	return ((l >> s) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT;
>  }
> @@ -112,7 +114,7 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI
>  	int s = ((lane & 1) ?
>  		 DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT :
>  		 DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT);
> -	u8 l = dp_link_status(link_status, i);
> +	u8 l = drm_dp_link_status(link_status, i);
>  
>  	return ((l >> s) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT;
>  }
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 06a478679781..9930b2b269f2 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -952,6 +952,9 @@
>  #define DP_MST_LOGICAL_PORT_0 8
>  
>  #define DP_LINK_STATUS_SIZE	   6
> +
> +u8 drm_dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r);
> +u8 drm_dp_get_lane_status(const u8 link_status[DP_LINK_STATUS_SIZE], int lane);
>  bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
>  			  int lane_count);
>  bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE],