Re: [PATCH v3 20/25] bus: mhi: ep: Add support for processing command ring

Manivannan Sadhasivam
2022-02-22T10:35:13Z

On Tue, Feb 15, 2022 at 04:40:01PM -0600, Alex Elder wrote:
> On 2/12/22 12:21 PM, Manivannan Sadhasivam wrote:
> > Add support for processing the command ring. Command ring is used by the
> > host to issue channel specific commands to the ep device. Following
> > commands are supported:
> >
> > 1. Start channel
> > 2. Stop channel
> > 3. Reset channel
> >
> > Once the device receives the command doorbell interrupt from host, it
> > executes the command and generates a command completion event to the
> > host in the primary event ring.
> >
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
>
> I'll let you consider my few comments below, but whether or not you
> address them, this looks OK to me.
>
> Reviewed-by: Alex Elder <elder@linaro.org>
>
> > ---
> > drivers/bus/mhi/ep/main.c | 151 ++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 151 insertions(+)
> >
> > diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
> > index 6378ac5c7e37..4c2ee517832c 100644
> > --- a/drivers/bus/mhi/ep/main.c
> > +++ b/drivers/bus/mhi/ep/main.c
> > @@ -21,6 +21,7 @@
> > static DEFINE_IDA(mhi_ep_cntrl_ida);
> > +static int mhi_ep_create_device(struct mhi_ep_cntrl *mhi_cntrl, u32 ch_id);
> > static int mhi_ep_destroy_device(struct device *dev, void *data);
> > static int mhi_ep_send_event(struct mhi_ep_cntrl *mhi_cntrl, u32 ring_idx,
> > @@ -185,6 +186,156 @@ void mhi_ep_unmap_free(struct mhi_ep_cntrl *mhi_cntrl, u64 pci_addr, phys_addr_t
> > mhi_cntrl->free_addr(mhi_cntrl, phys - offset, virt - offset, size);
> > }
> > +int mhi_ep_process_cmd_ring(struct mhi_ep_ring *ring, struct mhi_ep_ring_element *el)
> > +{
> > + struct mhi_ep_cntrl *mhi_cntrl = ring->mhi_cntrl;
> > + struct device *dev = &mhi_cntrl->mhi_dev->dev;
> > + struct mhi_result result = {};
> > + struct mhi_ep_chan *mhi_chan;
> > + struct mhi_ep_ring *ch_ring;
> > + u32 tmp, ch_id;
> > + int ret;
> > +
> > + ch_id = MHI_TRE_GET_CMD_CHID(el);
> > + mhi_chan = &mhi_cntrl->mhi_chan[ch_id];
> > + ch_ring = &mhi_cntrl->mhi_chan[ch_id].ring;
> > +
> > + switch (MHI_TRE_GET_CMD_TYPE(el)) {
>
> No MHI_PKT_TYPE_NOOP_CMD?
>

Not now.

> > + case MHI_PKT_TYPE_START_CHAN_CMD:
> > + dev_dbg(dev, "Received START command for channel (%d)\n", ch_id);
> > +
> > + mutex_lock(&mhi_chan->lock);
> > + /* Initialize and configure the corresponding channel ring */
> > + if (!ch_ring->started) {
> > + ret = mhi_ep_ring_start(mhi_cntrl, ch_ring,
> > + (union mhi_ep_ring_ctx *)&mhi_cntrl->ch_ctx_cache[ch_id]);
> > + if (ret) {
> > + dev_err(dev, "Failed to start ring for channel (%d)\n", ch_id);
> > + ret = mhi_ep_send_cmd_comp_event(mhi_cntrl,
> > + MHI_EV_CC_UNDEFINED_ERR);
> > + if (ret)
> > + dev_err(dev, "Error sending completion event (%d)\n",
> > + MHI_EV_CC_UNDEFINED_ERR);
>
> Print the value of ret in the above message (not UNDEFINED_ERR).
>
> > +
> > + goto err_unlock;
> > + }
> > + }
> > +
> > + /* Enable DB for the channel */
> > + mhi_ep_mmio_enable_chdb_a7(mhi_cntrl, ch_id);
>
> If an error occurs later, this will be enabled. Is that what
> you want? Maybe wait to enable the doorbell until everything
> else succeeds.
>

Makes sense. Will move this to the end.

> > +
> > + /* Set channel state to RUNNING */
> > + mhi_chan->state = MHI_CH_STATE_RUNNING;
> > + tmp = le32_to_cpu(mhi_cntrl->ch_ctx_cache[ch_id].chcfg);
> > + tmp &= ~CHAN_CTX_CHSTATE_MASK;
> > + tmp |= FIELD_PREP(CHAN_CTX_CHSTATE_MASK, MHI_CH_STATE_RUNNING);
> > + mhi_cntrl->ch_ctx_cache[ch_id].chcfg = cpu_to_le32(tmp);
> > +
> > + ret = mhi_ep_send_cmd_comp_event(mhi_cntrl, MHI_EV_CC_SUCCESS);
> > + if (ret) {
> > + dev_err(dev, "Error sending command completion event (%d)\n",
> > + MHI_EV_CC_SUCCESS);
> > + goto err_unlock;
> > + }
> > +
> > + mutex_unlock(&mhi_chan->lock);
> > +
> > + /*
> > + * Create MHI device only during UL channel start. Since the MHI
> > + * channels operate in a pair, we'll associate both UL and DL
> > + * channels to the same device.
> > + *
> > + * We also need to check for mhi_dev != NULL because, the host
> > + * will issue START_CHAN command during resume and we don't
> > + * destroy the device during suspend.
> > + */
> > + if (!(ch_id % 2) && !mhi_chan->mhi_dev) {
> > + ret = mhi_ep_create_device(mhi_cntrl, ch_id);
> > + if (ret) {
>
> If this occurs, the host will already have been told the
> request completed successfully. Is that a problem that
> can/should be avoided?
>

This should result in SYSERR. Will handle.

Thanks,
Mani