On Thu, 2017-05-11 at 14:20 +0200, Joakim Tjernlund wrote:
> Current I2C reset procedure is broken in two ways:
> 1) It only generate 1 START instead of 9 STARTs and STOP.
> 2) It leaves the bus Busy so every I2C xfer after the first
> fixup calls the reset routine again, for every xfer there after.
>
> This fixes both errors.
Ping?
>
> Signed-off-by: Joakim Tjernlund <joakim.tjernlund@xxxxxxxxxxxx>
> ---
>
> v2 - Remove io barrier call.
> drivers/i2c/busses/i2c-mpc.c | 23 +++++++++++++++--------
> 1 file changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
> index 8393140..6b5e6ce4 100644
> --- a/drivers/i2c/busses/i2c-mpc.c
> +++ b/drivers/i2c/busses/i2c-mpc.c
> @@ -104,23 +104,30 @@ static irqreturn_t mpc_i2c_isr(int irq, void *dev_id)
> /* 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 9 pulses, so it's all OK.
> + * the 9 pulses, each with a START then ending with STOP, so it's all OK.
> */
> static void mpc_i2c_fixup(struct mpc_i2c *i2c)
> {
> int k;
> - u32 delay_val = 1000000 / i2c->real_clk + 1;
> -
> - if (delay_val < 2)
> - delay_val = 2;
> + unsigned long flags;
>
> for (k = 9; k; k--) {
> writeccr(i2c, 0);
> - writeccr(i2c, CCR_MSTA | CCR_MTX | CCR_MEN);
> + writeb(0, i2c->base + MPC_I2C_SR); /* clear any status bits */
> + writeccr(i2c, CCR_MEN | CCR_MSTA); /* START */
> + readb(i2c->base + MPC_I2C_DR); /* init xfer */
> + udelay(15); /* let it hit the bus */
> + local_irq_save(flags); /* should not be delayed further */
> + writeccr(i2c, CCR_MEN | CCR_MSTA | CCR_RSTA); /* delay SDA */
> readb(i2c->base + MPC_I2C_DR);
> - writeccr(i2c, CCR_MEN);
> - udelay(delay_val << 1);
> + if (k != 1)
> + udelay(5);
> + local_irq_restore(flags);
> }
> + writeccr(i2c, CCR_MEN); /* Initiate STOP */
> + readb(i2c->base + MPC_I2C_DR);
> + udelay(15); /* Let STOP propagate */
> + writeccr(i2c, 0);
> }
>
> static int i2c_wait(struct mpc_i2c *i2c, unsigned timeout, int writing)
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