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Message-ID: <x4eixnu3kta6u2xqf6mn7ons2pupr7oe5fzjur2pfhgppmozoq@lgmk7zwqhcqm>
Date: Mon, 23 Sep 2024 15:00:27 +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>, 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 v3 3/3] drm/bridge: it6505: Add MCCS support
On Mon, Sep 23, 2024 at 05:48:29PM GMT, Hermes Wu wrote:
> From: Hermes Wu <Hermes.wu@....com.tw>
>
> Changes in v3:
> -remove non used definition for aux i2x cmd reply
>
> Add Aux-I2C functionality to support MCCS.
>
> Signed-off-by: Hermes Wu <Hermes.wu@....com.tw>
> ---
> drivers/gpu/drm/bridge/ite-it6505.c | 174 +++++++++++++++++++++++++++-
> 1 file changed, 172 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index 156440c6517e..5aedc5570739 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -125,6 +125,9 @@
> #define REG_AUX_ADR_16_19 0x26
> #define REG_AUX_OUT_DATA0 0x27
>
> +#define REG_AUX_I2C_ADR 0x25
> +#define REG_AUX_I2C_OP 0x26
> +
Are these registers CMD-specific? Because I see that you already have
defines for 0x25 and 0x26.
> #define REG_AUX_CMD_REQ 0x2B
> #define AUX_BUSY BIT(5)
>
> @@ -266,6 +269,19 @@
> #define REG_SSC_CTRL1 0x189
> #define REG_SSC_CTRL2 0x18A
>
> +#define REG_AUX_USER_CTRL 0x190
> +#define EN_USER_AUX BIT(0)
> +#define USER_AUX_DONE BIT(1)
> +#define AUX_EVENT BIT(4)
> +
> +#define REG_AUX_USER_DATA_REC 0x191
> +#define M_AUX_IN_REC 0xF0
> +#define M_AUX_OUT_REC 0x0F
> +
> +#define REG_AUX_USER_TXB 0x190
And two defines for 0x190 too.
> +#define REG_AUX_USER_REPLY 0x19A
> +#define REG_AUX_USER_RXB(n) (n + 0x19B)
> +
> #define RBR DP_LINK_BW_1_62
> #define HBR DP_LINK_BW_2_7
> #define HBR2 DP_LINK_BW_5_4
> @@ -301,6 +317,8 @@
> #define MAX_EQ_LEVEL 0x03
> #define AUX_WAIT_TIMEOUT_MS 15
> #define AUX_FIFO_MAX_SIZE 16
> +#define AUX_I2C_MAX_SIZE 4
> +#define AUX_I2C_DEFER_RETRY 4
> #define PIXEL_CLK_DELAY 1
> #define PIXEL_CLK_INVERSE 0
> #define ADJUST_PHASE_THRESHOLD 80000
> @@ -323,7 +341,12 @@
> enum aux_cmd_type {
> CMD_AUX_NATIVE_READ = 0x0,
> CMD_AUX_NATIVE_WRITE = 0x5,
> + CMD_AUX_GI2C_ADR = 0x08,
> + CMD_AUX_GI2C_READ = 0x09,
> + CMD_AUX_GI2C_WRITE = 0x0A,
> CMD_AUX_I2C_EDID_READ = 0xB,
> + CMD_AUX_I2C_READ = 0x0D,
> + CMD_AUX_I2C_WRITE = 0x0C,
>
> /* KSV list read using AUX native read with FIFO */
> CMD_AUX_GET_KSV_LIST = 0x10,
> @@ -1106,6 +1129,154 @@ static ssize_t it6505_aux_do_transfer(struct it6505 *it6505,
> return ret;
> }
>
> +static int it6505_aux_i2c_wait(struct it6505 *it6505, u8 *reply)
> +{
> + int err = 0;
Skip assignment here.
> + unsigned long timeout;
> + struct device *dev = it6505->dev;
> +
> + timeout = jiffies + msecs_to_jiffies(AUX_WAIT_TIMEOUT_MS) + 1;
> +
> + do {
> + if (it6505_read(it6505, REG_AUX_USER_CTRL) & AUX_EVENT)
> + break;
> + if (time_after(jiffies, timeout)) {
> + dev_err(dev, "Timed out waiting AUX I2C, BUSY = %X\n",
> + it6505_aux_op_finished(it6505));
> + err = -ETIMEDOUT;
> + goto end_aux_i2c_wait;
> + }
> + usleep_range(300, 800);
> + } while (!it6505_aux_op_finished(it6505));
> +
> + if (!reply)
> + goto end_aux_i2c_wait;
> +
> + *reply = it6505_read(it6505, REG_AUX_USER_REPLY) >> 4;
> +
> + if (*reply == 0)
> + goto end_aux_i2c_wait;
assign err = 0 here, so that it's obvious that it's a successfull case.
> +
> + if ((*reply == DP_AUX_NATIVE_REPLY_DEFER) ||
> + (*reply == DP_AUX_I2C_REPLY_DEFER))
> + err = -EBUSY;
> + else if ((*reply == DP_AUX_NATIVE_REPLY_NACK) ||
> + (*reply == DP_AUX_I2C_REPLY_NACK))
> + err = -ENXIO;
> +
> +end_aux_i2c_wait:
> + it6505_set_bits(it6505, REG_AUX_USER_CTRL, USER_AUX_DONE, USER_AUX_DONE);
> + return err;
> +}
> +
> +static int it6505_aux_i2c_readb(struct it6505 *it6505, u8 *buf, size_t size, u8 *reply)
> +{
> + int ret, i;
> + int retry = 0;
Skip the init
> +
> + for (retry = 0; retry < AUX_I2C_DEFER_RETRY; retry++) {
> + it6505_write(it6505, REG_AUX_CMD_REQ, CMD_AUX_GI2C_READ);
empty line
> + ret = it6505_aux_i2c_wait(it6505, reply);
> + if ((*reply == DP_AUX_NATIVE_REPLY_DEFER) ||
> + (*reply == DP_AUX_I2C_REPLY_DEFER))
These two lines keep on being repeated over and over. Please consider
defining a helper function.
> + continue;
> + if (ret >= 0)
> + break;
> + }
> +
> + for (i = 0; i < size; i++)
> + buf[i] = (u8)it6505_read(it6505, REG_AUX_USER_RXB(0 + i));
Single space, drop type conversion.
> +
> + return size;
> +}
> +
> +static int it6505_aux_i2c_writeb(struct it6505 *it6505, u8 *buf, size_t size, u8 *reply)
> +{
> + int i, ret;
> + int retry = 0;
> +
> + for (i = 0; i < size; i++)
> + it6505_write(it6505, REG_AUX_OUT_DATA0 + i, buf[i]);
> +
> + for (retry = 0; retry < AUX_I2C_DEFER_RETRY; retry++) {
> + it6505_write(it6505, REG_AUX_CMD_REQ, CMD_AUX_GI2C_WRITE);
empty line
> + ret = it6505_aux_i2c_wait(it6505, reply);
> + if ((*reply == DP_AUX_NATIVE_REPLY_DEFER) ||
> + (*reply == DP_AUX_I2C_REPLY_DEFER))
> + continue;
> + if (ret >= 0)
> + break;
> + }
> + return size;
> +}
> +
> +static ssize_t it6505_aux_i2c_operation(struct it6505 *it6505,
> + struct drm_dp_aux_msg *msg)
> +{
> + int ret;
> + ssize_t request_size, data_cnt = 0;
> + u8 *buffer = msg->buffer;
> +
> + /* set AUX user mode */
> + it6505_set_bits(it6505, REG_AUX_CTRL,
> + AUX_USER_MODE | AUX_NO_SEGMENT_WR, AUX_USER_MODE);
> + it6505_set_bits(it6505, REG_AUX_USER_CTRL, EN_USER_AUX, EN_USER_AUX);
> + /* clear AUX FIFO */
> + it6505_set_bits(it6505, REG_AUX_CTRL,
> + AUX_EN_FIFO_READ | CLR_EDID_FIFO,
> + AUX_EN_FIFO_READ | CLR_EDID_FIFO);
> +
> + it6505_set_bits(it6505, REG_AUX_CTRL,
> + AUX_EN_FIFO_READ | CLR_EDID_FIFO, 0x00);
> +
> + it6505_write(it6505, REG_AUX_ADR_0_7, 0x00);
> + it6505_write(it6505, REG_AUX_I2C_ADR, msg->address << 1);
> +
> + if (msg->size == 0) {
> + /* IIC Start/STOP dummy write */
> + it6505_write(it6505, REG_AUX_I2C_OP, msg->request);
> + it6505_write(it6505, REG_AUX_CMD_REQ, CMD_AUX_GI2C_ADR);
> + ret = it6505_aux_i2c_wait(it6505, &msg->reply);
> + goto end_aux_i2c_transfer;
> + }
> +
> + /* IIC data transfer */
> + for (data_cnt = 0; data_cnt < msg->size; ) {
> + request_size = min_t(ssize_t, msg->size - data_cnt, AUX_I2C_MAX_SIZE);
> + it6505_write(it6505, REG_AUX_I2C_OP,
> + msg->request | ((request_size - 1) << 4));
> + if ((msg->request & DP_AUX_I2C_READ) == DP_AUX_I2C_READ)
> + ret = it6505_aux_i2c_readb(it6505, &buffer[data_cnt],
> + request_size, &msg->reply);
> + else
> + ret = it6505_aux_i2c_writeb(it6505, &buffer[data_cnt],
> + request_size, &msg->reply);
> +
> + if (ret < 0)
> + goto end_aux_i2c_transfer;
> +
> + data_cnt += request_size;
> + }
> + ret = data_cnt;
> +end_aux_i2c_transfer:
> +
> + it6505_set_bits(it6505, REG_AUX_USER_CTRL, EN_USER_AUX, 0);
> + it6505_set_bits(it6505, REG_AUX_CTRL, AUX_USER_MODE, 0);
> + return ret;
> +}
> +
> +static ssize_t it6505_aux_i2c_transfer(struct drm_dp_aux *aux,
> + struct drm_dp_aux_msg *msg)
> +{
> + struct it6505 *it6505 = container_of(aux, struct it6505, aux);
> + int ret;
> +
> + mutex_lock(&it6505->aux_lock);
> + ret = it6505_aux_i2c_operation(it6505, msg);
> + mutex_unlock(&it6505->aux_lock);
Is it enough to protect from other commands sending data in parallel?
Also as much as I don't like it, in this case using guard() from
cleanup.h will remove a need for a separte function.
> + return ret;
> +}
> +
> static ssize_t it6505_aux_transfer(struct drm_dp_aux *aux,
> struct drm_dp_aux_msg *msg)
> {
> @@ -1115,9 +1286,8 @@ static ssize_t it6505_aux_transfer(struct drm_dp_aux *aux,
> int ret;
> enum aux_cmd_reply reply;
>
> - /* IT6505 doesn't support arbitrary I2C read / write. */
> if (is_i2c)
> - return -EINVAL;
> + return it6505_aux_i2c_transfer(aux, msg);
>
> switch (msg->request) {
> case DP_AUX_NATIVE_READ:
> --
> 2.34.1
>
--
With best wishes
Dmitry
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