On Tue 31 Mar 04:23 PDT 2020, Manivannan Sadhasivam wrote:

Hi Bjorn,

On Mon, Mar 30, 2020 at 03:19:32PM -0700, Bjorn Andersson wrote:

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On Mon 30 Mar 02:49 PDT 2020, Manivannan Sadhasivam wrote:

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Hi Chris,

On Thu, Mar 26, 2020 at 03:54:42PM -0700, Chris Lew wrote:

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On 3/25/2020 3:37 AM, Manivannan Sadhasivam wrote:

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Hi Bjorn,

+ Chris Lew

On Tue, Mar 24, 2020 at 01:39:52PM -0700, Bjorn Andersson wrote:

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On Mon 23 Mar 23:10 PDT 2020, Manivannan Sadhasivam wrote:

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+	spin_lock_irqsave(&qdev->ul_lock, flags);
+	list_for_each_entry(pkt, &qdev->ul_pkts, node)
+		complete_all(&pkt->done);

Chris, shouldn't we require list_del(&pkt->node) here?

No this isn't a full cleanup, with the "early notifier" we just unblocked
any threads waiting for the ul_callback. Those threads will wake, check
in_reset, return an error back to the caller. Any list cleanup will be done
in the ul_callbacks that the mhi bus will do for each queued packet right
before device remove.

Again to simplify the code, we can probable remove the in_reset handling
since it's not required with the current feature set.

So since we are not getting status_cb for fatal errors, I think we should just
remove status_cb, in_reset and timeout code.

Looks reasonable.

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I thought having the client get an error on timeout and resend the packet
would be better than silently dropping it. In practice, we've really only
seen the timeout or ul_callback errors on unrecoverable errors so I think
the timeout handling can definitely be redone.

You mean we can just remove the timeout handling part and return after
kref_put()?

If all messages are "generated" by qcom_mhi_qrtr_send() and "released"
in qcom_mhi_qrtr_ul_callback() I don't think you need the refcounting at
all.

Hmm, you're right. We can move the packet releasing part to ul_callback now.

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Presumably though, it would have been nice to not have to carry a
separate list of packets (and hope that it's in sync with the mhi core)
and instead have the ul callback somehow allow us to derive the skb to
be freed.

Yep, MHI stack holds the skb in buf_addr member of mhi_result. So, we can just
use below to get the skb in ul_callback:

struct sk_buff *skb = (struct sk_buff *)mhi_res->buf_addr;

This will help us to avoid the use of pkt, ul_pkts list and use the skb directly
everywhere. At the same time I think we can also remove the ul_lock which
was added to protect the ul_pkts list.

Let me know your opinion, I'll just send a series with this modified QRTR MHI
client driver and MHI suspend/resume patches.

This looks more robust than having the separate list shadowing the
internal state of the MHI core.

+1

Thanks,
Bjorn