FusionHDTV: Use quick reads for I2C IR device probing

IR support on FusionHDTV cards is broken since kernel 2.6.31. One side effect of the switch to the standard binding model for IR I2C devices was to let i2c-core do the probing instead of the ir-kbd-i2c driver. There is a slight difference between the two probe methods: i2c-core uses 0-byte writes, while the ir-kbd-i2c was using 0-byte reads. As some IR I2C devices only support reads, the new probe method fails to detect them.

For now, revert to letting the driver do the probe, using 0-byte reads. In the future, i2c-core will be extended to let callers of i2c_new_probed_device() provide a custom probing function.

Signed-off-by Jean Delvare <[email protected]>

Tested-by "Timothy D. Lenz" <[email protected]>

---
This fix applies to kernels 2.6.31 to 2.6.34. Should be sent to Linus quickly. I had already sent on March 29th, but apparently it was overlooked. I have further i2c patches which depend on this one, so please process it quickly, otherwise I'll have to push it myself.

 drivers/media/video/cx23885/cx23885-i2c.c |   12 +++++++++++-
 drivers/media/video/cx88/cx88-i2c.c       |   16 +++++++++++++++-
 2 files changed, 26 insertions(+), 2 deletions(-)

drivers/media/video/cx23885/cx23885-i2c.c +11 -1

@@ -365,7 +365,17 @@ int cx23885_i2c_register(struct cx23885_
 
 		memset(&info, 0, sizeof(struct i2c_board_info));
 		strlcpy(info.type, "ir_video", I2C_NAME_SIZE);
-		i2c_new_probed_device(&bus->i2c_adap, &info, addr_list);
+		/*
+		 * We can't call i2c_new_probed_device() because it uses
+		 * quick writes for probing and the IR receiver device only
+		 * replies to reads.
+		 */
+		if (i2c_smbus_xfer(&bus->i2c_adap, addr_list[0], 0,
+				   I2C_SMBUS_READ, 0, I2C_SMBUS_QUICK,
+				   NULL) >= 0) {
+			info.addr = addr_list[0];
+			i2c_new_device(&bus->i2c_adap, &info);
+		}
 	}
 
 	return bus->i2c_rc;

drivers/media/video/cx88/cx88-i2c.c +15 -1

@@ -188,10 +188,24 @@ int cx88_i2c_init(struct cx88_core *core
 			0x18, 0x6b, 0x71,
 			I2C_CLIENT_END
 		};
+		const unsigned short *addrp;
 
 		memset(&info, 0, sizeof(struct i2c_board_info));
 		strlcpy(info.type, "ir_video", I2C_NAME_SIZE);
-		i2c_new_probed_device(&core->i2c_adap, &info, addr_list);
+		/*
+		 * We can't call i2c_new_probed_device() because it uses
+		 * quick writes for probing and at least some R receiver
+		 * devices only reply to reads.
+		 */
+		for (addrp = addr_list; *addrp != I2C_CLIENT_END; addrp++) {
+			if (i2c_smbus_xfer(&core->i2c_adap, *addrp, 0,
+					   I2C_SMBUS_READ, 0,
+					   I2C_SMBUS_QUICK, NULL) >= 0) {
+				info.addr = *addrp;
+				i2c_new_device(&core->i2c_adap, &info);
+				break;
+			}
+		}
 	}
 	return core->i2c_rc;
 }

Mauro,

Quoted 12 lines · Jean Delvare

IR support on FusionHDTV cards is broken since kernel 2.6.31. One side effect of the switch to the standard binding model for IR I2C devices was to let i2c-core do the probing instead of the ir-kbd-i2c driver. There is a slight difference between the two probe methods: i2c-core uses 0-byte writes, while the ir-kbd-i2c was using 0-byte reads. As some IR I2C devices only support reads, the new probe method fails to detect them.

For now, revert to letting the driver do the probe, using 0-byte reads. In the future, i2c-core will be extended to let callers of i2c_new_probed_device() provide a custom probing function.

Quoted 7 lines

Signed-off-by Jean Delvare <[email protected]>

Tested-by "Timothy D. Lenz" <[email protected]>

---
This fix applies to kernels 2.6.31 to 2.6.34. Should be sent to Linus quickly. I had already sent on March 29th, but apparently it was overlooked. I have further i2c patches which depend on this one, so please process it quickly, otherwise I'll have to push it myself.

This fix is still not upstream! What do I have to do to get it there? Please!