On Tue, Mar 17, 2015 at 05:22:08PM +0200, Jani Nikula wrote:
> On Fri, 13 Mar 2015, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> >
> > When an i2c WRITE gets an i2c defer or short i2c ack reply, we are
> > supposed to switch the request from I2C_WRITE to I2C_WRITE_STATUS_UPDATE
> > when we continue to poll for the completion of the request.
>
> As I said IRL, it's a bit unfortunate that setting and resetting of
> DP_AUX_I2C_WRITE_STATUS_UPDATE happen at different levels of the
> abstraction. But I can live with that.
>
> We also have another problem with reporting short writes in i915,
> hopefully fixed by [1]. Before that gets fixed, can't really r-b.
>
> BR,
> Jani.
>
>
> [1] http://mid.gmane.org/1426605534-5780-1-git-send-email-jani.nikula at
> intel.com
BTW I notice now that radeon seems to have that same problem. I won't
try to fix that, so just a FYI for the radeon folks...
>
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > ---
> > drivers/gpu/drm/drm_dp_helper.c | 41
> > +++++++++++++++++++++++++++++++++++++----
> > 1 file changed, 37 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_dp_helper.c
> > b/drivers/gpu/drm/drm_dp_helper.c
> > index d5368ea..4db81a6 100644
> > --- a/drivers/gpu/drm/drm_dp_helper.c
> > +++ b/drivers/gpu/drm/drm_dp_helper.c
> > @@ -422,6 +422,25 @@ static u32 drm_dp_i2c_functionality(struct i2c_adapter
> > *adapter)
> > I2C_FUNC_10BIT_ADDR;
> > }
> >
> > +static void drm_dp_i2c_msg_set_request(struct drm_dp_aux_msg *msg,
> > + const struct i2c_msg *i2c_msg)
> > +{
> > + msg->request = (i2c_msg->flags & I2C_M_RD) ?
> > + DP_AUX_I2C_READ : DP_AUX_I2C_WRITE;
> > + msg->request |= DP_AUX_I2C_MOT;
> > +}
> > +
> > +static void drm_dp_i2c_msg_write_status_update(struct drm_dp_aux_msg *msg)
> > +{
> > + /*
> > + * In case of i2c defer or short i2c ack reply to a write,
> > + * we need to switch to WRITE_STATUS_UPDATE to drain the
> > + * rest of the message
> > + */
> > + if ((msg->request & ~DP_AUX_I2C_MOT) == DP_AUX_I2C_WRITE)
> > + msg->request |= DP_AUX_I2C_WRITE_STATUS_UPDATE;
> > +}
> > +
> > /*
> > * Transfer a single I2C-over-AUX message and handle various error
> > conditions,
> > * retrying the transaction as appropriate. It is assumed that the
> > @@ -490,6 +509,8 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux,
> > struct drm_dp_aux_msg *msg)
> > * Both native ACK and I2C ACK replies received. We
> > * can assume the transfer was successful.
> > */
> > + if (ret != msg->size)
> > + drm_dp_i2c_msg_write_status_update(msg);
> > return ret;
> >
> > case DP_AUX_I2C_REPLY_NACK:
> > @@ -501,6 +522,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux,
> > struct drm_dp_aux_msg *msg)
> > DRM_DEBUG_KMS("I2C defer\n");
> > aux->i2c_defer_count++;
> > usleep_range(400, 500);
> > + drm_dp_i2c_msg_write_status_update(msg);
> > continue;
> >
> > default:
> > @@ -566,10 +588,7 @@ static int drm_dp_i2c_xfer(struct i2c_adapter
> > *adapter, struct i2c_msg *msgs,
> >
> > for (i = 0; i < num; i++) {
> > msg.address = msgs[i].addr;
> > - msg.request = (msgs[i].flags & I2C_M_RD) ?
> > - DP_AUX_I2C_READ :
> > - DP_AUX_I2C_WRITE;
> > - msg.request |= DP_AUX_I2C_MOT;
> > + drm_dp_i2c_msg_set_request(&msg, &msgs[i]);
> > /* Send a bare address packet to start the transaction.
> > * Zero sized messages specify an address only (bare
> > * address) transaction.
> > @@ -577,6 +596,13 @@ static int drm_dp_i2c_xfer(struct i2c_adapter
> > *adapter, struct i2c_msg *msgs,
> > msg.buffer = NULL;
> > msg.size = 0;
> > err = drm_dp_i2c_do_msg(aux, &msg);
> > +
> > + /*
> > + * Reset msg.request in case in case it got
> > + * changed into a WRITE_STATUS_UPDATE.
> > + */
> > + drm_dp_i2c_msg_set_request(&msg, &msgs[i]);
> > +
> > if (err < 0)
> > break;
> > /* We want each transaction to be as large as possible, but
> > @@ -589,6 +615,13 @@ static int drm_dp_i2c_xfer(struct i2c_adapter
> > *adapter, struct i2c_msg *msgs,
> > msg.size = min(transfer_size, msgs[i].len - j);
> >
> > err = drm_dp_i2c_drain_msg(aux, &msg);
> > +
> > + /*
> > + * Reset msg.request in case in case it got
> > + * changed into a WRITE_STATUS_UPDATE.
> > + */
> > + drm_dp_i2c_msg_set_request(&msg, &msgs[i]);
> > +
> > if (err < 0)
> > break;
> > transfer_size = err;
> > --
> > 2.0.5
> >
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/dri-devel
>
> --
> Jani Nikula, Intel Open Source Technology Center
--
Ville Syrjälä
Intel OTC
