> Date: Mon, 21 May 2018 17:25:47 -0700
> From: Mike Larkin <[email protected]>
>
> On Mon, May 21, 2018 at 12:44:47PM +0200, Mark Kettenis wrote:
> > The diff below fixes I2C_OP_WRITE_WITH_STOP operations. Currently we
> > run the read completion code for those operations, but since there is
> > no data to read, this fails. Instead, this waits until a stop is
> > detected. That doesn't seem to work for I2C_F_POLL operations though,
> > so in that case we wait until the bus is idle. This also adds
> > interlocks (using splbio/splx) on the existing tsleep() operations.
> >
> > This doesn't fix all the issues with the driver. In particular it
> > seems that large reads still cause problems. I think a somewhat more
> > invasive re-write of the dwiic_i2c_exec() function is needed. But I'd
> > like to get this in before I embark on that.
> >
> > ok?
> >
>
> The diff reads ok to me, do you want us to do any sort of testing here before
> commit?
Testing is always appreciated, and a goood idea if you own a machine
that relies on dwiic(4). For example those with machines that have a
keyboard or touchpad/screen connected over i2c.
Cheers,
Mark
> > Index: dev/ic/dwiic.c
> > ===================================================================
> > RCS file: /cvs/src/sys/dev/ic/dwiic.c,v
> > retrieving revision 1.3
> > diff -u -p -r1.3 dwiic.c
> > --- dev/ic/dwiic.c 19 Jan 2018 18:20:38 -0000 1.3
> > +++ dev/ic/dwiic.c 21 May 2018 10:37:50 -0000
> > @@ -192,6 +192,7 @@ dwiic_i2c_exec(void *cookie, i2c_op_t op
> > u_int32_t ic_con, st, cmd, resp;
> > int retries, tx_limit, rx_avail, x, readpos;
> > uint8_t *b;
> > + int s;
> >
> > if (sc->sc_busy)
> > return 1;
> > @@ -245,12 +246,14 @@ dwiic_i2c_exec(void *cookie, i2c_op_t op
> > if (flags & I2C_F_POLL)
> > DELAY(200);
> > else {
> > + s = splbio();
> > dwiic_read(sc, DW_IC_CLR_INTR);
> > dwiic_write(sc, DW_IC_INTR_MASK, DW_IC_INTR_TX_EMPTY);
> >
> > if (tsleep(&sc->sc_writewait, PRIBIO, "dwiic", hz / 2) != 0)
> > printf("%s: timed out waiting for tx_empty intr\n",
> > sc->sc_dev.dv_xname);
> > + splx(s);
> > }
> >
> > /* send our command, one byte at a time */
> > @@ -320,7 +323,7 @@ dwiic_i2c_exec(void *cookie, i2c_op_t op
> > * As TXFLR fills up, we need to clear it out by reading all
> > * available data.
> > */
> > - while (tx_limit == 0 || x == len) {
> > + while (I2C_OP_READ_P(op) && (tx_limit == 0 || x == len)) {
> > DPRINTF(("%s: %s: tx_limit %d, sent %d read reqs\n",
> > sc->sc_dev.dv_xname, __func__, tx_limit, x));
> >
> > @@ -332,6 +335,7 @@ dwiic_i2c_exec(void *cookie, i2c_op_t op
> > DELAY(50);
> > }
> > } else {
> > + s = splbio();
> > dwiic_read(sc, DW_IC_CLR_INTR);
> > dwiic_write(sc, DW_IC_INTR_MASK,
> > DW_IC_INTR_RX_FULL);
> > @@ -341,6 +345,7 @@ dwiic_i2c_exec(void *cookie, i2c_op_t op
> > printf("%s: timed out waiting for "
> > "rx_full intr\n",
> > sc->sc_dev.dv_xname);
> > + splx(s);
> >
> > rx_avail = dwiic_read(sc, DW_IC_RXFLR);
> > }
> > @@ -378,6 +383,32 @@ dwiic_i2c_exec(void *cookie, i2c_op_t op
> > }
> > }
> >
> > + if (I2C_OP_STOP_P(op) && I2C_OP_WRITE_P(op)) {
> > + if (flags & I2C_F_POLL) {
> > + /* wait for bus to be idle */
> > + for (retries = 100; retries > 0; retries--) {
> > + st = dwiic_read(sc, DW_IC_STATUS);
> > + if (!(st & DW_IC_STATUS_ACTIVITY))
> > + break;
> > + DELAY(1000);
> > + }
> > + if (st & DW_IC_STATUS_ACTIVITY)
> > + printf("%s: timed out waiting for bus idle\n",
> > + sc->sc_dev.dv_xname);
> > + } else {
> > + s = splbio();
> > + while (sc->sc_busy) {
> > + dwiic_write(sc, DW_IC_INTR_MASK,
> > + DW_IC_INTR_STOP_DET);
> > + if (tsleep(&sc->sc_busy, PRIBIO, "dwiic",
> > + hz / 2) != 0)
> > + printf("%s: timed out waiting for "
> > + "stop intr\n",
> > + sc->sc_dev.dv_xname);
> > + }
> > + splx(s);
> > + }
> > + }
> > sc->sc_busy = 0;
> >
> > return 0;
> > @@ -449,6 +480,11 @@ dwiic_intr(void *arg)
> > DPRINTF(("%s: %s: waking up writer\n",
> > sc->sc_dev.dv_xname, __func__));
> > wakeup(&sc->sc_writewait);
> > + }
> > + if (stat & DW_IC_INTR_STOP_DET) {
> > + dwiic_write(sc, DW_IC_INTR_MASK, 0);
> > + sc->sc_busy = 0;
> > + wakeup(&sc->sc_busy);
> > }
> > }
> >
> >
>
