Commit 3b384bd6 authored by Furquan Shaikh's avatar Furquan Shaikh Committed by Dmitry Torokhov
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Input: raydium_ts_i2c - do not split tx transactions 



Raydium device does not like splitting of tx transactions into multiple
messages - one for the register address and one for the actual data. This
results in incorrect behavior on the device side.

This change updates raydium_i2c_read and raydium_i2c_write to create
i2c_msg arrays separately and passes those arrays into raydium_i2c_xfer
which decides based on the address whether the bank switch command should
be sent. The bank switch header is still added by raydium_i2c_read and
raydium_i2c_write to ensure that all these operations are performed as part
of a single I2C transfer. It guarantees that no other transactions are
initiated to any other device on the same bus after the bank switch command
is sent.

Signed-off-by: default avatarFurquan Shaikh <furquan@google.com>
Link: https://lore.kernel.org/r/20201205005941.1427643-1-furquan@google.com


Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 8c3b55a2

drivers/input/touchscreen/raydium_i2c_ts.c

+88 −38
Original line number Diff line number Diff line
@@ -137,45 +137,25 @@ struct raydium_data { 
	bool wake_irq_enabled;

};



static int raydium_i2c_xfer(struct i2c_client *client,

			    u32 addr, void *data, size_t len, bool is_read)

{

	struct raydium_bank_switch_header {

/*

 * Header to be sent for RM_CMD_BANK_SWITCH command. This is used by

 * raydium_i2c_{read|send} below.

 */

struct __packed raydium_bank_switch_header {

	u8 cmd;

	__be32 be_addr;

	} __packed header = {

		.cmd = RM_CMD_BANK_SWITCH,

		.be_addr = cpu_to_be32(addr),

};



	u8 reg_addr = addr & 0xff;



	struct i2c_msg xfer[] = {

		{

			.addr = client->addr,

			.len = sizeof(header),

			.buf = (u8 *)&header,

		},

		{

			.addr = client->addr,

			.len = 1,

			.buf = &reg_addr,

		},

static int raydium_i2c_xfer(struct i2c_client *client, u32 addr,

			    struct i2c_msg *xfer, size_t xfer_count)

{

			.addr = client->addr,

			.len = len,

			.buf = data,

			.flags = is_read ? I2C_M_RD : 0,

		}

	};



	int ret;

	/*

	 * If address is greater than 255, then RM_CMD_BANK_SWITCH needs to be

	 * sent first. Else, skip the header i.e. xfer[0].

	 */

	int xfer_start_idx = (addr > 0xff) ? 0 : 1;

	size_t xfer_count = ARRAY_SIZE(xfer) - xfer_start_idx;

	int ret;

	xfer_count -= xfer_start_idx;



	ret = i2c_transfer(client->adapter, &xfer[xfer_start_idx], xfer_count);

	if (likely(ret == xfer_count))
@@ -189,10 +169,46 @@ static int raydium_i2c_send(struct i2c_client *client, 
{

	int tries = 0;

	int error;

	u8 *tx_buf;

	u8 reg_addr = addr & 0xff;



	tx_buf = kmalloc(len + 1, GFP_KERNEL);

	if (!tx_buf)

		return -ENOMEM;



	tx_buf[0] = reg_addr;

	memcpy(tx_buf + 1, data, len);



	do {

		error = raydium_i2c_xfer(client, addr, (void *)data, len,

					 false);

		struct raydium_bank_switch_header header = {

			.cmd = RM_CMD_BANK_SWITCH,

			.be_addr = cpu_to_be32(addr),

		};



		/*

		 * Perform as a single i2c_transfer transaction to ensure that

		 * no other I2C transactions are initiated on the bus to any

		 * other device in between. Initiating transacations to other

		 * devices after RM_CMD_BANK_SWITCH is sent is known to cause

		 * issues. This is also why regmap infrastructure cannot be used

		 * for this driver. Regmap handles page(bank) switch and reads

		 * as separate i2c_transfer() operations. This can result in

		 * problems if the Raydium device is on a shared I2C bus.

		 */

		struct i2c_msg xfer[] = {

			{

				.addr = client->addr,

				.len = sizeof(header),

				.buf = (u8 *)&header,

			},

			{

				.addr = client->addr,

				.len = len + 1,

				.buf = tx_buf,

			},

		};



		error = raydium_i2c_xfer(client, addr, xfer, ARRAY_SIZE(xfer));

		if (likely(!error))

			return 0;
@@ -206,12 +222,46 @@ static int raydium_i2c_send(struct i2c_client *client, 
static int raydium_i2c_read(struct i2c_client *client,

			    u32 addr, void *data, size_t len)

{

	size_t xfer_len;

	int error;



	while (len) {

		xfer_len = min_t(size_t, len, RM_MAX_READ_SIZE);

		error = raydium_i2c_xfer(client, addr, data, xfer_len, true);

		u8 reg_addr = addr & 0xff;

		struct raydium_bank_switch_header header = {

			.cmd = RM_CMD_BANK_SWITCH,

			.be_addr = cpu_to_be32(addr),

		};

		size_t xfer_len = min_t(size_t, len, RM_MAX_READ_SIZE);



		/*

		 * Perform as a single i2c_transfer transaction to ensure that

		 * no other I2C transactions are initiated on the bus to any

		 * other device in between. Initiating transacations to other

		 * devices after RM_CMD_BANK_SWITCH is sent is known to cause

		 * issues. This is also why regmap infrastructure cannot be used

		 * for this driver. Regmap handles page(bank) switch and writes

		 * as separate i2c_transfer() operations. This can result in

		 * problems if the Raydium device is on a shared I2C bus.

		 */

		struct i2c_msg xfer[] = {

			{

				.addr = client->addr,

				.len = sizeof(header),

				.buf = (u8 *)&header,

			},

			{

				.addr = client->addr,

				.len = 1,

				.buf = &reg_addr,

			},

			{

				.addr = client->addr,

				.len = xfer_len,

				.buf = data,

				.flags = I2C_M_RD,

			}

		};



		error = raydium_i2c_xfer(client, addr, xfer, ARRAY_SIZE(xfer));

		if (unlikely(error))

			return error;

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