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Subject: media: dw2102: Don't translate i2c read into write Author: Michael Bunk <mi...@freedict.org> Date: Sun Jan 16 11:22:36 2022 +0000 The code ignored the I2C_M_RD flag on I2C messages. Instead it assumed an i2c transaction with a single message must be a write operation and a transaction with two messages would be a read operation. Though this works for the driver code, it leads to problems once the i2c device is exposed to code not knowing this convention. For example, I did "insmod i2c-dev" and issued read requests from userspace, which were translated into write requests and destroyed the EEPROM of my device. So, just check and respect the I2C_M_READ flag, which indicates a read when set on a message. If it is absent, it is a write message. Incidentally, changing from the case statement to a while loop allows the code to lift the limitation to two i2c messages per transaction. There are 4 more *_i2c_transfer functions affected by the same behaviour and limitation that should be fixed in the same way. Link: https://lore.kernel.org/linux-media/20220116112238.74171-2-mi...@freedict.org Signed-off-by: Michael Bunk <mi...@freedict.org> Signed-off-by: Mauro Carvalho Chehab <mche...@kernel.org> drivers/media/usb/dvb-usb/dw2102.c | 120 ++++++++++++++++++++++--------------- 1 file changed, 73 insertions(+), 47 deletions(-) --- diff --git a/drivers/media/usb/dvb-usb/dw2102.c b/drivers/media/usb/dvb-usb/dw2102.c index b3bb1805829a..10351308b0d0 100644 --- a/drivers/media/usb/dvb-usb/dw2102.c +++ b/drivers/media/usb/dvb-usb/dw2102.c @@ -716,6 +716,7 @@ static int su3000_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[], { struct dvb_usb_device *d = i2c_get_adapdata(adap); struct dw2102_state *state; + int j; if (!d) return -ENODEV; @@ -729,11 +730,11 @@ static int su3000_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[], return -EAGAIN; } - switch (num) { - case 1: - switch (msg[0].addr) { + j = 0; + while (j < num) { + switch (msg[j].addr) { case SU3000_STREAM_CTRL: - state->data[0] = msg[0].buf[0] + 0x36; + state->data[0] = msg[j].buf[0] + 0x36; state->data[1] = 3; state->data[2] = 0; if (dvb_usb_generic_rw(d, state->data, 3, @@ -745,61 +746,86 @@ static int su3000_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[], if (dvb_usb_generic_rw(d, state->data, 1, state->data, 2, 0) < 0) err("i2c transfer failed."); - msg[0].buf[1] = state->data[0]; - msg[0].buf[0] = state->data[1]; + msg[j].buf[1] = state->data[0]; + msg[j].buf[0] = state->data[1]; break; default: - if (3 + msg[0].len > sizeof(state->data)) { - warn("i2c wr: len=%d is too big!\n", - msg[0].len); + /* if the current write msg is followed by a another + * read msg to/from the same address + */ + if ((j+1 < num) && (msg[j+1].flags & I2C_M_RD) && + (msg[j].addr == msg[j+1].addr)) { + /* join both i2c msgs to one usb read command */ + if (4 + msg[j].len > sizeof(state->data)) { + warn("i2c combined wr/rd: write len=%d is too big!\n", + msg[j].len); + num = -EOPNOTSUPP; + break; + } + if (1 + msg[j+1].len > sizeof(state->data)) { + warn("i2c combined wr/rd: read len=%d is too big!\n", + msg[j+1].len); + num = -EOPNOTSUPP; + break; + } + + state->data[0] = 0x09; + state->data[1] = msg[j].len; + state->data[2] = msg[j+1].len; + state->data[3] = msg[j].addr; + memcpy(&state->data[4], msg[j].buf, msg[j].len); + + if (dvb_usb_generic_rw(d, state->data, msg[j].len + 4, + state->data, msg[j+1].len + 1, 0) < 0) + err("i2c transfer failed."); + + memcpy(msg[j+1].buf, &state->data[1], msg[j+1].len); + j++; + break; + } + + if (msg[j].flags & I2C_M_RD) { + /* single read */ + if (1 + msg[j].len > sizeof(state->data)) { + warn("i2c rd: len=%d is too big!\n", msg[j].len); + num = -EOPNOTSUPP; + break; + } + + state->data[0] = 0x09; + state->data[1] = 0; + state->data[2] = msg[j].len; + state->data[3] = msg[j].addr; + memcpy(&state->data[4], msg[j].buf, msg[j].len); + + if (dvb_usb_generic_rw(d, state->data, 4, + state->data, msg[j].len + 1, 0) < 0) + err("i2c transfer failed."); + + memcpy(msg[j].buf, &state->data[1], msg[j].len); + break; + } + + /* single write */ + if (3 + msg[j].len > sizeof(state->data)) { + warn("i2c wr: len=%d is too big!\n", msg[j].len); num = -EOPNOTSUPP; break; } - /* always i2c write*/ state->data[0] = 0x08; - state->data[1] = msg[0].addr; - state->data[2] = msg[0].len; + state->data[1] = msg[j].addr; + state->data[2] = msg[j].len; - memcpy(&state->data[3], msg[0].buf, msg[0].len); + memcpy(&state->data[3], msg[j].buf, msg[j].len); - if (dvb_usb_generic_rw(d, state->data, msg[0].len + 3, + if (dvb_usb_generic_rw(d, state->data, msg[j].len + 3, state->data, 1, 0) < 0) err("i2c transfer failed."); + } // switch + j++; - } - break; - case 2: - /* always i2c read */ - if (4 + msg[0].len > sizeof(state->data)) { - warn("i2c rd: len=%d is too big!\n", - msg[0].len); - num = -EOPNOTSUPP; - break; - } - if (1 + msg[1].len > sizeof(state->data)) { - warn("i2c rd: len=%d is too big!\n", - msg[1].len); - num = -EOPNOTSUPP; - break; - } - - state->data[0] = 0x09; - state->data[1] = msg[0].len; - state->data[2] = msg[1].len; - state->data[3] = msg[0].addr; - memcpy(&state->data[4], msg[0].buf, msg[0].len); - - if (dvb_usb_generic_rw(d, state->data, msg[0].len + 4, - state->data, msg[1].len + 1, 0) < 0) - err("i2c transfer failed."); - - memcpy(msg[1].buf, &state->data[1], msg[1].len); - break; - default: - warn("more than 2 i2c messages at a time is not handled yet."); - break; - } + } // while mutex_unlock(&d->data_mutex); mutex_unlock(&d->i2c_mutex); return num;
