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Input: raydium_ts_i2c - do not split tx transactions

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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: Furquan Shaikh <furquan@google.com>
Link: https://lore.kernel.org/r/20201205005941.1427643-1-furquan@google.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Furquan Shaikh 2020-12-06 22:05:13 -08:00 committed by Dmitry Torokhov
parent 8c3b55a299
commit 3b384bd6c3
1 changed files with 88 additions and 38 deletions
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126
drivers/input/touchscreen/raydium_i2c_ts.c
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@ -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)
/*
* 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;
};
static int raydium_i2c_xfer(struct i2c_client *client, u32 addr,
struct i2c_msg *xfer, size_t xfer_count)
{
struct 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,
},
{
.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;