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From: Pavel Butsykin <pbutsykin@virtuozzo.com>
Message-ID: <56F40393.20505@virtuozzo.com>
Date: Thu, 24 Mar 2016 18:11:15 +0300
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Subject: Re: [Qemu-devel] [PATCH 1/3] ide: don't loose pending dma state
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To: Paolo Bonzini <pbonzini@redhat.com>, "Denis V. Lunev" <den@openvz.org>, qemu-devel@nongnu.org
Cc: John Snow <jsnow@redhat.com>

On 24.03.2016 17:07, Paolo Bonzini wrote:
>
>
> On 24/03/2016 14:38, Pavel Butsykin wrote:
>> Look at the ide_sector_read_cb function. The ->dma_cmd field is used
>> only for the DMA, we can't use the ide_cmd_is_read macro for PIO or
>> ATAPI. In fact, the ide_handle_rw_error looks like a generic function
>> and I do not see any good reason to move the handling of the dma_cmd
>> field(especially in the context of bug fixes).
>
> I agree now.
>
>>> However, if it works, using dma_cmd would be better than using the
>>> dma_cb.
>>>
>> We can't use the dma_cmd field to build the ATAPI ->error_status. Your
>> proposal is quite logical, but please look at the 3rd patch, there to
>> build ->error_status we can use the same dma_cb, it is very convenient.
>
> Couldn't you just add a new dma_cmd value IDE_DMA_ATAPI, and set it
> before every call to ide_start_dma(s, ide_atapi_cmd_read_dma_cb)?
>
You want something like this:
dma_cb()
{
...
     if (ret < 0) {
         if (ide_handle_rw_error(s, -ret, ide_dma_cmd_to_retry(s))) {
             return;
         }
     }
...
}

static void ide_bmdma_pre_save(void *opaque)
{
...
     if (!(bm->status & BM_STATUS_DMAING) && bm->dma_cb) {
         bm->bus->error_status = ide_dma_cmd_to_retry(bmdma_active_if(bm));
     }
...
}

??

> Thanks,
>
> Paolo
>