linux-kernel - RE: [PATCH] RFC: mmc: dw_mmc: Always go to STATE_DATA_BUSY from STATE_DATA

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Message-id: <003401ce3453$19d1e8c0$4d75ba40$%jun@samsung.com>
Date:	Mon, 08 Apr 2013 21:17:55 +0900
From:	Seungwon Jeon <tgih.jun@...sung.com>
To:	'Jaehoon Chung' <jh80.chung@...sung.com>,
	'Doug Anderson' <dianders@...omium.org>
Cc:	'Chris Ball' <cjb@...top.org>,
	'Will Newton' <will.newton@...il.com>,
	'Bing Zhao' <bzhao@...vell.com>,
	'Ashok Nagarajan' <asnagarajan@...omium.org>,
	'Paul Stewart' <pstew@...omium.org>,
	'Olof Johansson' <olof@...om.net>, linux-mmc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: RE: [PATCH] RFC: mmc: dw_mmc: Always go to STATE_DATA_BUSY from
 STATE_DATA_ERROR

On Friday, April 05, 2013, Jaehoon Chung wrote:
> Hi Doug,
> 
> You're right..it's something wrong.
> Actually i didn't test with your patch, but your commit message is reasonable.
> 
> I will check until next week after test.
Doug Anderson, Jaehoon Chung,

Sorry for late response.
Could I explain this problem more?
I guess Doug are debugging it with wifi, right?
The problem happens when dw_mci_stop_dma is called in the middle of data transfers.
If data error occurs in the end of block, EVENT_XFER_COMPLETE might be set. So, it's fine.
Actually, dw_mci_idmac_stop_dma stops the dma working, there is no further interrupt for dma completion.
There are two solutions we have applied.

#1. deferring the call of dw_mci_stop_dma until EVENT_XFER_COMPLETE flag is set into pending_events.
In this case, dma transfer will be continued with error.

@@ -1062,7 +1062,6 @@ static void dw_mci_tasklet_func(unsigned long priv)
                case STATE_SENDING_DATA:
                        if (test_and_clear_bit(EVENT_DATA_ERROR,
                                               &host->pending_events)) {
-                               dw_mci_stop_dma(host);
                                if (data->stop)
                                        send_stop_cmd(host, data);
                                state = STATE_DATA_ERROR;
@@ -1155,6 +1154,9 @@ static void dw_mci_tasklet_func(unsigned long priv)
                                                &host->pending_events))
                                break;

+                       dw_mci_stop_dma(host);
+                       set_bit(EVENT_XFER_COMPLETE, &host->completed_events);
+
                        state = STATE_DATA_BUSY;
                        break;
                        
#2. set EVENT_XFER_COMPLETE flag when dw_mci_stop_dma is called regardless using_dma.

@@ -299,10 +299,9 @@ static void dw_mci_stop_dma(struct dw_mci *host)
        if (host->using_dma) {
                host->dma_ops->stop(host);
                host->dma_ops->cleanup(host);
-       } else {
-               /* Data transfer was stopped by the interrupt handler */
-               set_bit(EVENT_XFER_COMPLETE, &host->pending_events);
        }
+
+       set_bit(EVENT_XFER_COMPLETE, &host->pending_events);
 }

If you have any opinion, please let me know.

Thanks,
Seungwon Jeon 
> 
> Best Regards,
> Jaehoon Chung
> 
> On 03/27/2013 03:06 AM, Doug Anderson wrote:
> > Jaehoon,
> >
> > On Mon, Mar 18, 2013 at 3:21 AM, Jaehoon Chung <jh80.chung@...sung.com> wrote:
> >> Hi Doug,
> >>
> >> Great..i have found the problem like this.
> >> I will check your patch..and share the result.
> >
> > Did you have any time to check this patch?
> >
> > Thanks!
> >
> > -Doug
> >
> 
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