From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH v3] i2c: rk3x: fix bug that cause transfer fails in master receive mode Date: Fri, 22 Aug 2014 09:16:41 -0700 Message-ID: <20140822161641.GA12900@core.coreip.homeip.net> References: <1408657107-8715-1-git-send-email-addy.ke@rock-chips.com> <1408669991-9703-1-git-send-email-addy.ke@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1408669991-9703-1-git-send-email-addy.ke-TNX95d0MmH7DzftRWevZcw@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Addy Ke Cc: wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org, max.schwarz-BGeptl67XyCzQB+pC5nmwQ@public.gmane.org, heiko-4mtYJXux2i+zQB+pC5nmwQ@public.gmane.org, olof-nZhT3qVonbNeoWH0uzbU5w@public.gmane.org, dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, sergei.shtylyov-M4DtvfQ/ZS1MRgGoP+s0PdBPR1lH4CV8@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, cf-TNX95d0MmH7DzftRWevZcw@public.gmane.org, xjq-TNX95d0MmH7DzftRWevZcw@public.gmane.org, huangtao-TNX95d0MmH7DzftRWevZcw@public.gmane.org, zyw-TNX95d0MmH7DzftRWevZcw@public.gmane.org, yzq-TNX95d0MmH7DzftRWevZcw@public.gmane.org, hj-TNX95d0MmH7DzftRWevZcw@public.gmane.org, kever.yang-TNX95d0MmH7DzftRWevZcw@public.gmane.org, hl-TNX95d0MmH7DzftRWevZcw@public.gmane.org, caesar.wang-TNX95d0MmH7DzftRWevZcw@public.gmane.org, zhengsq-TNX95d0MmH7DzftRWevZcw@public.gmane.org List-Id: linux-i2c@vger.kernel.org Hi Addy, 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 > Signed-off-by: Addy Ke > --- > 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 often. Thanks. -- Dmitry