Re: [PATCH v2] HID: i2c-hid: Use block reads when possible to save power

[Sultan Alsawaf <sultan@kerneltoast.com>]

On Wed, Jul 01, 2020 at 11:04:01AM +0300, Jarkko Nikula wrote:
> On 6/29/20 8:43 PM, Sultan Alsawaf wrote:
> > Hmm, for some reason in 5.8 I get the same problem, but 5.7 is fine. Could you
> > try this on 5.7 and see if it works?
> > 
> > In the meantime I'll bisect 5.8 to see why it's causing problems for me...
> > 
> I see the same issue on top of v5.7:

Try reverting my "i2c: designware: Only check the first byte for SMBus block
read length" patch and apply the following change instead:

--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -394,10 +394,12 @@ i2c_dw_read(struct dw_i2c_dev *dev)
 			u32 flags = msgs[dev->msg_read_idx].flags;
 
 			*buf = dw_readl(dev, DW_IC_DATA_CMD);
-			/* Ensure length byte is a valid value */
-			if (flags & I2C_M_RECV_LEN &&
-				*buf <= I2C_SMBUS_BLOCK_MAX && *buf > 0) {
-				len = i2c_dw_recv_len(dev, *buf);
+			if (flags & I2C_M_RECV_LEN) {
+				/* Ensure length byte is a valid value */
+				if (*buf <= I2C_SMBUS_BLOCK_MAX && *buf > 0)
+					len = i2c_dw_recv_len(dev, *buf);
+				else
+					len = i2c_dw_recv_len(dev, len);
 			}
 			buf++;
 			dev->rx_outstanding--;