On Tue, 2017-05-16 at 17:13 +0200, Joakim Tjernlund wrote:
> 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?
Ping again, pretty please?
>
> >
> > 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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