[PATCH v3] i2c: rk3x: fix bug that cause transfer fails in master receive mode
dmitry.torokhov at gmail.com
Fri Aug 22 09:16:41 PDT 2014
On Fri, Aug 22, 2014 at 09:13:11AM +0800, Addy Ke wrote:
> In rk3x SOC, the I2C controller can receive/transmit up to 32 bytes data
> in one chunk, so the size of data to be write/read to/from TXDATAx/RXDATAx
> must be less than or equal 32 bytes at a time.
> Tested on rk3288-pinky board, elan receive 158 bytes data.
> Acked-by: Max Schwarz <max.schwarz at online.de>
> Signed-off-by: Addy Ke <addy.ke at rock-chips.com>
> Changes in v2:
> - Use cleaner syntax as suggested by Sergei.
> - Update commit message as suggested by Wolfram.
> Changes in v3:
> - fix typo: maste --> master and double spaces after 'len'
> drivers/i2c/busses/i2c-rk3x.c | 4 ++++
> 1 file changed, 4 insertions(+)
> diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
> index 69e1185..806724a 100644
> --- a/drivers/i2c/busses/i2c-rk3x.c
> +++ b/drivers/i2c/busses/i2c-rk3x.c
> @@ -323,6 +323,10 @@ static void rk3x_i2c_handle_read(struct rk3x_i2c *i2c, unsigned int ipd)
> /* ack interrupt */
> i2c_writel(i2c, REG_INT_MBRF, REG_IPD);
> + /* Can only handle a maximum of 32 bytes at a time */
> + if (unlikely(len > 32))
> + len = 32;
I do not think we should be using unlikely here (and in another spot in the
driver): unlikely should be used only if the condition happens extremely
infrequently in all of the systems. Here, if a box happens to have a device
that uses transfers larger than 32 bytes we'd be hitting unlikely branch pretty
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