On 11/07/07 00:03 -0600, Grant Likely wrote: > On 7/10/07, Domen Puncer <[EMAIL PROTECTED]> wrote: > >On 10/07/07 14:40 +0200, Jean Delvare wrote: ... > >+/* Sometimes 9th clock pulse isn't generated, so slave doesn't release > >+ * the bus. Documented and suggested workaround on > >+ * http://ozlabs.org/pipermail/linuxppc-embedded/2005-July/019038.html > >+ */ > > I don't think it's a great idea to use a link; You should copy the > important parts into the .c file. Archives may not be forever, and > links cannot be read when offline. If the text is too long for the > middle of the C file; then put the documentation at the top right > after the header block.
And v4: <----------- cut -------------> Work around a problem reported on: http://ozlabs.org/pipermail/linuxppc-embedded/2005-July/019038.html Without this patch I2C on mpc5200 becomes unusable after a while. Tested on mpc5200 boards by Matthias Fechner and me. Signed-off-by: Domen Puncer <[EMAIL PROTECTED]> --- drivers/i2c/busses/i2c-mpc.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) Index: work-powerpc.git/drivers/i2c/busses/i2c-mpc.c =================================================================== --- work-powerpc.git.orig/drivers/i2c/busses/i2c-mpc.c +++ work-powerpc.git/drivers/i2c/busses/i2c-mpc.c @@ -74,6 +74,25 @@ static irqreturn_t mpc_i2c_isr(int irq, return IRQ_HANDLED; } +/* Sometimes 9th clock pulse isn't generated, and slave doesn't release + * the bus, because it wants to send ACK. + * Following sequence of enabling/disabling and sending start/stop generates + * the pulse, so it's all OK. + */ +static void mpc_i2c_fixup(struct mpc_i2c *i2c) +{ + writeccr(i2c, 0); + udelay(30); + writeccr(i2c, CCR_MEN); + udelay(30); + writeccr(i2c, CCR_MSTA | CCR_MTX); + udelay(30); + writeccr(i2c, CCR_MSTA | CCR_MTX | CCR_MEN); + udelay(30); + writeccr(i2c, CCR_MEN); + udelay(30); +} + static int i2c_wait(struct mpc_i2c *i2c, unsigned timeout, int writing) { unsigned long orig_jiffies = jiffies; @@ -153,6 +172,7 @@ static void mpc_i2c_start(struct mpc_i2c static void mpc_i2c_stop(struct mpc_i2c *i2c) { writeccr(i2c, CCR_MEN); + writeccr(i2c, 0); } static int mpc_write(struct mpc_i2c *i2c, int target, @@ -245,6 +265,8 @@ static int mpc_xfer(struct i2c_adapter * } if (time_after(jiffies, orig_jiffies + HZ)) { pr_debug("I2C: timeout\n"); + if (readb(i2c->base + MPC_I2C_SR) == (CSR_MCF | CSR_MBB | CSR_RXAK)) + mpc_i2c_fixup(i2c); return -EIO; } schedule(); _______________________________________________ Linuxppc-embedded mailing list [email protected] https://ozlabs.org/mailman/listinfo/linuxppc-embedded
