Date:	Fri, 5 Aug 2016 18:08:17 +0800
From:	CK Hu <ck.hu@...iatek.com>
To:	YT Shen <yt.shen@...iatek.com>
CC:	<dri-devel@...ts.freedesktop.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	"Mark Rutland" <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	"Russell King" <linux@....linux.org.uk>,
	David Airlie <airlied@...ux.ie>,
	"Matthias Brugger" <matthias.bgg@...il.com>,
	Mao Huang <littlecvr@...omium.org>,
	"Bibby Hsieh" <bibby.hsieh@...iatek.com>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-mediatek@...ts.infradead.org>,
	<srv_heupstream@...iatek.com>,
	"Sascha Hauer" <kernel@...gutronix.de>,
	<yingjoe.chen@...iatek.com>, <emil.l.velikov@...il.com>,
	<thierry.reding@...il.com>,
	shaoming chen <shaoming.chen@...iatek.com>
Subject: Re: [PATCH v6 07/10] drm/mediatek: add dsi transfer function

Hi, YT:

On Thu, 2016-08-04 at 19:07 +0800, YT Shen wrote:
> From: shaoming chen <shaoming.chen@...iatek.com>
> 
> add dsi read/write commands for transfer function
> 
> Signed-off-by: shaoming chen <shaoming.chen@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dsi.c |  261 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 261 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index eea6192..4541f59 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -24,6 +24,7 @@
>  #include <linux/of_graph.h>
>  #include <linux/phy/phy.h>
>  #include <linux/platform_device.h>
> +#include <video/mipi_display.h>
>  #include <video/videomode.h>
>  
>  #include "mtk_drm_ddp_comp.h"
> @@ -81,8 +82,16 @@
>  #define DSI_HBP_WC		0x54
>  #define DSI_HFP_WC		0x58
>  
> +#define DSI_CMDQ_SIZE		0x60
> +#define CMDQ_SIZE		0x3f
> +
>  #define DSI_HSTX_CKL_WC		0x64
>  
> +#define DSI_RX_DATA0		0x74
> +#define DSI_RX_DATA1		0x78
> +#define DSI_RX_DATA2		0x7c
> +#define DSI_RX_DATA3		0x80
> +
>  #define DSI_RACK		0x84
>  #define RACK				BIT(0)
>  
> @@ -118,8 +127,25 @@
>  #define CLK_HS_POST			(0xff << 8)
>  #define CLK_HS_EXIT			(0xff << 16)
>  
> +#define DSI_CMDQ0		0x180
> +
>  #define NS_TO_CYCLE(n, c)    ((n) / (c) + (((n) % (c)) ? 1 : 0))
>  
> +#define MTK_DSI_HOST_IS_READ(type) \
> +	((type == MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM) || \
> +	(type == MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM) || \
> +	(type == MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM) || \
> +	(type == MIPI_DSI_DCS_READ))
> +
> +#define MTK_DSI_HOST_IS_WRITE(type) \
> +	((type == MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM) || \
> +	(type == MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM) || \
> +	(type == MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM) || \
> +	(type == MIPI_DSI_DCS_SHORT_WRITE) || \
> +	(type == MIPI_DSI_DCS_SHORT_WRITE_PARAM) || \
> +	(type == MIPI_DSI_GENERIC_LONG_WRITE) || \
> +	(type == MIPI_DSI_DCS_LONG_WRITE))
> +
>  struct phy;
>  
>  struct mtk_dsi {
> @@ -149,6 +175,13 @@ struct mtk_dsi {
>  	int irq_data;
>  };
>  
> +struct dsi_rxtx_data {
> +	u8 byte0;
> +	u8 byte1;
> +	u8 byte2;
> +	u8 byte3;
> +};
> +
>  static wait_queue_head_t _dsi_irq_wait_queue;
>  
>  static inline struct mtk_dsi *encoder_to_dsi(struct drm_encoder *e)
> @@ -799,9 +832,237 @@ static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
>  	return 0;
>  }
>  
> +static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
> +{
> +	u32 timeout_ms = 500000; /* total 1s ~ 2s timeout */
> +
> +	while (timeout_ms--) {
> +		if (!(readl(dsi->regs + DSI_INTSTA) & DSI_BUSY))
> +			break;
> +
> +		usleep_range(2, 4);
> +	}
> +
> +	if (timeout_ms == 0) {
> +		dev_info(dsi->dev, "polling dsi wait not busy timeout!\n");
> +
> +		mtk_dsi_enable(dsi);
> +		mtk_dsi_reset_engine(dsi);
> +	}
> +}
> +
> +static void mtk_dsi_wait_for_cmd_done(struct mtk_dsi *dsi)
> +{
> +	s32 ret = 0;
> +	unsigned long timeout = msecs_to_jiffies(500);
> +
> +	dsi->irq_data &= ~CMD_DONE_INT_FLAG;

You should move this clearing of flag before mtk_dsi_start().

> +
> +	ret = wait_event_interruptible_timeout(_dsi_irq_wait_queue,
> +			dsi->irq_data & CMD_DONE_INT_FLAG, timeout);
> +	if (ret == 0) {
> +		dev_info(dsi->dev, "dsi wait engine cmd done fail\n");
> +
> +		mtk_dsi_enable(dsi);
> +		mtk_dsi_reset_engine(dsi);
> +	}
> +}
> +
> +static void mtk_dsi_cmdq(struct mtk_dsi *dsi, const struct mipi_dsi_msg *msg)
> +{
> +	const char *tx_buf = msg->tx_buf;
> +	u32 reg_val, i;
> +	u16 wc16;
> +	u8 config, data0, data1, type;
> +
> +	if (MTK_DSI_HOST_IS_READ(type)) {

'type' is used before assigned.

> +		config = 4;
> +		data0 = tx_buf[0];
> +
> +		if (msg->rx_len < 3)
> +			type = MIPI_DSI_DCS_READ;
> +		else
> +			type = MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM;
> +
> +		data1 = 0;
> +		reg_val = (data1 << 24) | (data0 << 16) | (type << 8) | config;
> +
> +		writel(reg_val, dsi->regs + DSI_CMDQ0);
> +		mtk_dsi_mask(dsi, DSI_CMDQ_SIZE, CMDQ_SIZE, 1);

I think this part looks like 'else' part. The difference is type and
config. I think type should be msg->type and you can independently set
BIT(2) of config.

> +	} else if (msg->tx_len > 2) {	/* send long packet */
> +		config = 2;
> +		type = msg->type;
> +		wc16 = msg->tx_len;
> +
> +		reg_val = (wc16 << 16) | (type << 8) | config;
> +
> +		writel(reg_val, dsi->regs + DSI_CMDQ0);
> +
> +		for (i = 0; i < msg->tx_len; i++)
> +			writeb(tx_buf[i], dsi->regs + DSI_CMDQ0 + 4 + i);
> +
> +		mtk_dsi_mask(dsi, DSI_CMDQ_SIZE, CMDQ_SIZE,
> +			     1 + (msg->tx_len + 3) / 4);
> +	} else {	/* send short packet */
> +		config = 0;
> +		data0 = tx_buf[0];
> +
> +		if (msg->tx_len == 2) {
> +			type = MIPI_DSI_DCS_SHORT_WRITE_PARAM;

Why do you not set type as msg->type? This behavior looks like you
modify transfer type, but is this acceptable?

> +			data1 = tx_buf[1];
> +		} else {
> +			type = MIPI_DSI_DCS_SHORT_WRITE;
> +			data1 = 0;
> +		}
> +
> +		reg_val = (data1 << 24) | (data0 << 16) | (type << 8) | config;
> +
> +		writel(reg_val, dsi->regs + DSI_CMDQ0);
> +		mtk_dsi_mask(dsi, DSI_CMDQ_SIZE, CMDQ_SIZE, 1);
> +	}
> +}
> +
> +static ssize_t mtk_dsi_host_read_cmd(struct mtk_dsi *dsi,
> +				     const struct mipi_dsi_msg *msg)
> +{
> +	u8 max_try_count = 5;
> +	u32 recv_cnt;
> +	struct dsi_rxtx_data read_data[4];
> +	s32 ret;
> +	unsigned long timeout = msecs_to_jiffies(2000);
> +
> +	u8 *buffer = msg->rx_buf;
> +	u8 buffer_size = msg->rx_len;
> +	u8 type;
> +
> +	if (readl(dsi->regs + DSI_MODE_CTRL) & MODE) {
> +		dev_info(dsi->dev, "dsi engine is not command mode\n");
> +		return -1;
> +	}
> +
> +	if (!buffer) {
> +		dev_info(dsi->dev, "dsi receive buffer size may be NULL\n");
> +		return -1;
> +	}
> +
> +	do {
> +		if (max_try_count == 0) {
> +			dev_info(dsi->dev, "dsi engine read counter has been maxinum\n");
> +			return -1;
> +		}
> +
> +		max_try_count--;
> +		recv_cnt = 0;
> +
> +		mtk_dsi_wait_for_idle(dsi);
> +		mtk_dsi_cmdq(dsi, msg);
> +
> +		dsi->irq_data &= ~LPRX_RD_RDY_INT_FLAG;
> +
> +		mtk_dsi_start(dsi);
> +
> +		/* 2s timeout*/
> +		ret = wait_event_interruptible_timeout(_dsi_irq_wait_queue,
> +				dsi->irq_data & LPRX_RD_RDY_INT_FLAG, timeout);
> +		if (ret == 0) {
> +			dev_info(dsi->dev, "Wait DSI read ready timeout!!!\n");
> +
> +			mtk_dsi_enable(dsi);
> +			mtk_dsi_reset_engine(dsi);
> +
> +			return ret;
> +		}

This waiting code looks like mtk_dsi_wait_for_cmd_done(). You may modify
this function to

int mtk_dsi_wait_for_irq_flag(struct mtk_dsi *dsi, u32 flag, unsigned
long timeout);

> +
> +		*(u32 *)(&read_data[0]) = readl(dsi->regs + DSI_RX_DATA0);
> +		*(u32 *)(&read_data[1]) = readl(dsi->regs + DSI_RX_DATA1);
> +		*(u32 *)(&read_data[2]) = readl(dsi->regs + DSI_RX_DATA2);
> +		*(u32 *)(&read_data[3]) = readl(dsi->regs + DSI_RX_DATA3);

You may rewrite this as

for (i = 0; i < 16; i++)
	*((u8 *)read_data + i) = readb(dsi->regs + DSI_RX_DATA0 + i);

> +
> +		type = read_data[0].byte0;
> +
> +		if (type == MIPI_DSI_RX_GENERIC_LONG_READ_RESPONSE ||
> +		    type == MIPI_DSI_RX_DCS_LONG_READ_RESPONSE) {
> +			/*
> +			 * Data ID(1 byte) + Word Count(2 bytes) + ECC(1 byte) +
> +			 * data 0 + ...+ data WC-1 + CHECKSUM (2 bytes)
> +			 */
> +			recv_cnt = read_data[0].byte1 + read_data[0].byte2 * 16;
> +			dev_info(dsi->dev, "long packet size: %d\n", recv_cnt);
> +
> +			/*
> +			 * the buffer size is 16 bytes once, so the data payload
> +			 * is, 16 - bytes(data ID + WC + ECC + CHECKSUM), if
> +			 * over 10 bytes, it will be read again
> +			 */
> +			if (recv_cnt > 10)
> +				recv_cnt = 10;
> +
> +			if (recv_cnt > buffer_size)
> +				recv_cnt = buffer_size;
> +
> +			memcpy(buffer, &read_data[1], recv_cnt);
> +		} else if (type == MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_1BYTE ||
> +			   type == MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_2BYTE ||
> +			   type == MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_1BYTE ||
> +			   type == MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_2BYTE) {
> +			if (type == MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_1BYTE ||
> +			    type == MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_1BYTE)
> +				recv_cnt = 1;
> +			else
> +				recv_cnt = 2;
> +
> +			if (recv_cnt > buffer_size)
> +				recv_cnt = buffer_size;
> +
> +			memcpy(buffer, &read_data[0].byte1, recv_cnt);

I think you may rewrite this 'if-else if' part as follow to make things
more clearly.

static u32 get_recv_cnt(u8 type, struct dsi_rxtx_data *read_data)
{
	switch(type) {
	case MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_1BYTE:
	case MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_1BYTE:
		return 1;
	case MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_2BYTE:
	case MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_2BYTE:
		return 2;
	case MIPI_DSI_RX_GENERIC_LONG_READ_RESPONSE:
	case MIPI_DSI_RX_DCS_LONG_READ_RESPONSE:
		return read_data->byte1 + read_data->byte2 * 16;
	}

	return 0;
}

recv_cnt = get_recv_cnt(type, read_data);

if (recv_cnt > 2)
	src_addr = &read_data[1];
else
	src_addr = &read_data[0].byte1;

if (recv_cnt > 10)
	recv_cnt = 10;
if (recv_cnt > buffer_size)
	recv_cnt = buffer_size;
if (recv_cnt)
	memcpy(buffer, src_addr, recv_cnt);

> +		} else if (type == MIPI_DSI_RX_ACKNOWLEDGE_AND_ERROR_REPORT) {
> +			dev_info(dsi->dev, "packet type is 0x02, try again\n");
> +		} else {
> +			dev_info(dsi->dev, "packet type(0x%x) cannot be non-recognize\n",
> +				 type);
> +
> +			return 0;
> +		}
> +	} while (type == MIPI_DSI_RX_ACKNOWLEDGE_AND_ERROR_REPORT);
> +
> +	dev_info(dsi->dev, "dsi get %d byte data from the panel address(0x%x)\n",
> +		 recv_cnt, *((u8 *)(msg->tx_buf)));
> +
> +	return recv_cnt;
> +}
> +
> +static ssize_t mtk_dsi_host_write_cmd(struct mtk_dsi *dsi,
> +				      const struct mipi_dsi_msg *msg)
> +{
> +	mtk_dsi_wait_for_idle(dsi);
> +
> +	mtk_dsi_cmdq(dsi, msg);
> +
> +	mtk_dsi_start(dsi);
> +	mtk_dsi_wait_for_cmd_done(dsi);
> +
> +	return 0;
> +}
> +
> +static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
> +				     const struct mipi_dsi_msg *msg)
> +{
> +	struct mtk_dsi *dsi = host_to_dsi(host);
> +	u8 type = msg->type;
> +	ssize_t ret = 0;
> +
> +	if (MTK_DSI_HOST_IS_READ(type))
> +		ret = mtk_dsi_host_read_cmd(dsi, msg);
> +	else if (MTK_DSI_HOST_IS_WRITE(type))
> +		ret = mtk_dsi_host_write_cmd(dsi, msg);
> +
> +	return ret;
> +}
> +
>  static const struct mipi_dsi_host_ops mtk_dsi_ops = {
>  	.attach = mtk_dsi_host_attach,
>  	.detach = mtk_dsi_host_detach,
> +	.transfer = mtk_dsi_host_transfer,
>  };
>  
>  static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)

Regards,
CK

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