linux-kernel - Re: [PATCH v5 03/10] drm/bridge: it6505: add AUX operation for HDCP KSV list read

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Message-ID: <2nceoodtqfspaxs5ipmrezivknexqwi4yc4mr4lak6yjgowpz5@evhz3vy45lb4>
Date: Mon, 14 Oct 2024 14:52:44 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Hermes Wu <Hermes.Wu@....com.tw>
Cc: Pin-yen Lin <treapking@...omium.org>, 
	Kenneth Hung <Kenneth.hung@....com.tw>, Pet Weng <Pet.Weng@....com.tw>, 
	Andrzej Hajda <andrzej.hajda@...el.com>, Neil Armstrong <neil.armstrong@...aro.org>, 
	Robert Foss <rfoss@...nel.org>, Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
	Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>, 
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 03/10] drm/bridge: it6505: add AUX operation for HDCP
 KSV list read

On Tue, Oct 01, 2024 at 02:43:02PM +0800, Hermes Wu wrote:
> From: Hermes Wu <Hermes.wu@....com.tw>
> 
> HDCP KSV list readback can choose to use AUX FIFO or general data register.
> For some DisplayPort devices, the KSV list must be read in 5 byte boundaries.
> The original AUX read command does not support these devices.
> 
> The AUX command operation control register "REG_AUX_CMD_REQ" uses b[3:0] as AUX operacion control, and b[7:4] are status bits and read only.
> To change KSV read operation uses "CMD_AUX_NATIVE_READ" from using the data registers to using AUX FIFO.
> The extended command "CMD_AUX_GET_KSV_LIST" is added as "CMD_AUX_NATIVE_READ" with the 0x10 flag which selects AUX FIFO mode.

Please keep the commit message wrapped at 72-75 chars.

Other than that:


Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>


> 
> Signed-off-by: Hermes Wu <Hermes.wu@....com.tw>
> ---
>  drivers/gpu/drm/bridge/ite-it6505.c | 16 +++++++++++-----
>  1 file changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index 864fab7e388f..9a022c095af4 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -126,6 +126,7 @@
>  #define REG_AUX_OUT_DATA0 0x27
>  
>  #define REG_AUX_CMD_REQ 0x2B
> +#define M_AUX_REQ_CMD 0x0F
>  #define AUX_BUSY BIT(5)
>  
>  #define REG_AUX_DATA_0_7 0x2C
> @@ -324,6 +325,9 @@ enum aux_cmd_type {
>  	CMD_AUX_NATIVE_READ = 0x0,
>  	CMD_AUX_NATIVE_WRITE = 0x5,
>  	CMD_AUX_I2C_EDID_READ = 0xB,
> +
> +	/* KSV read with AUX FIFO extend from CMD_AUX_NATIVE_READ*/
> +	CMD_AUX_GET_KSV_LIST = 0x10,
>  };
>  
>  enum aux_cmd_reply {
> @@ -965,7 +969,8 @@ static ssize_t it6505_aux_operation(struct it6505 *it6505,
>  	it6505_set_bits(it6505, REG_AUX_CTRL, AUX_USER_MODE, AUX_USER_MODE);
>  
>  aux_op_start:
> -	if (cmd == CMD_AUX_I2C_EDID_READ) {
> +	/* HW AUX FIFO supports only EDID and DCPD KSV FIFO area */
> +	if (cmd == CMD_AUX_I2C_EDID_READ || cmd == CMD_AUX_GET_KSV_LIST) {
>  		/* AUX EDID FIFO has max length of AUX_FIFO_MAX_SIZE bytes. */
>  		size = min_t(size_t, size, AUX_FIFO_MAX_SIZE);
>  		/* Enable AUX FIFO read back and clear FIFO */
> @@ -996,7 +1001,7 @@ static ssize_t it6505_aux_operation(struct it6505 *it6505,
>  				  size);
>  
>  	/* Aux Fire */
> -	it6505_write(it6505, REG_AUX_CMD_REQ, cmd);
> +	it6505_write(it6505, REG_AUX_CMD_REQ, FIELD_GET(M_AUX_REQ_CMD, cmd));
>  
>  	ret = it6505_aux_wait(it6505);
>  	if (ret < 0)
> @@ -1030,7 +1035,7 @@ static ssize_t it6505_aux_operation(struct it6505 *it6505,
>  		goto aux_op_start;
>  	}
>  
> -	if (cmd == CMD_AUX_I2C_EDID_READ) {
> +	if (cmd == CMD_AUX_I2C_EDID_READ || cmd == CMD_AUX_GET_KSV_LIST) {
>  		for (i = 0; i < size; i++) {
>  			ret = it6505_read(it6505, REG_AUX_DATA_FIFO);
>  			if (ret < 0)
> @@ -1055,7 +1060,7 @@ static ssize_t it6505_aux_operation(struct it6505 *it6505,
>  	ret = i;
>  
>  aux_op_err:
> -	if (cmd == CMD_AUX_I2C_EDID_READ) {
> +	if (cmd == CMD_AUX_I2C_EDID_READ || cmd == CMD_AUX_GET_KSV_LIST) {
>  		/* clear AUX FIFO */
>  		it6505_set_bits(it6505, REG_AUX_CTRL,
>  				AUX_EN_FIFO_READ | CLR_EDID_FIFO,
> @@ -1076,7 +1081,8 @@ static ssize_t it6505_aux_do_transfer(struct it6505 *it6505,
>  				      size_t size, enum aux_cmd_reply *reply)
>  {
>  	int i, ret_size, ret = 0, request_size;
> -	int fifo_max_size = (cmd == CMD_AUX_I2C_EDID_READ) ? AUX_FIFO_MAX_SIZE : 4;
> +	int fifo_max_size = (cmd == CMD_AUX_I2C_EDID_READ || cmd == CMD_AUX_GET_KSV_LIST) ?
> +						 AUX_FIFO_MAX_SIZE : 4;
>  
>  	mutex_lock(&it6505->aux_lock);
>  	i = 0;
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry