On 07/14/2016 04:37 PM, Tejun Heo wrote:
> Hello,
>
> I'm still a bit confused about this patch.
>
> On Thu, Jul 14, 2016 at 09:05:45AM +0900, Christoph Hellwig wrote:
>> diff --git a/drivers/ata/sata_fsl.c b/drivers/ata/sata_fsl.c
>> index a723ae9..acfb865 100644
>> --- a/drivers/ata/sata_fsl.c
>> +++ b/drivers/ata/sata_fsl.c
>> @@ -534,7 +534,7 @@ static void sata_fsl_qc_prep(struct ata_queued_cmd *qc)
>> VPRINTK("Dumping cfis : 0x%x, 0x%x, 0x%x\n",
>> cd->cfis[0], cd->cfis[1], cd->cfis[2]);
>>
>> - if (qc->tf.protocol == ATA_PROT_NCQ) {
>> + if (ata_is_fpdma(qc->tf.protocol)) {
>
> ata_is_fpdma() tests NCQ or DMA. Is this right?
>
Yes. The 'sata_fsl' driver has no means (or at least none which I could
detect) allowing it to send NCQ NON-DATA commands.
So for this driver the check for ncq is actually a check for fpdma.
>> --- a/drivers/ata/sata_mv.c
>> +++ b/drivers/ata/sata_mv.c
>> @@ -1173,7 +1173,7 @@ static void mv_set_irq_coalescing(struct ata_host *host,
>> static void mv_start_edma(struct ata_port *ap, void __iomem *port_mmio,
>> struct mv_port_priv *pp, u8 protocol)
>> {
>> - int want_ncq = (protocol == ATA_PROT_NCQ);
>> + int want_ncq = (ata_is_fpdma(protocol));
>
> Let's get rid of the parentheses while at it.
>
Okay.
>>
>> if (pp->pp_flags & MV_PP_FLAG_EDMA_EN) {
>> int using_ncq = ((pp->pp_flags & MV_PP_FLAG_NCQ_EN) != 0);
>> @@ -2156,8 +2156,7 @@ static void mv_qc_prep_iie(struct ata_queued_cmd *qc)
>> unsigned in_index;
>> u32 flags = 0;
>>
>> - if ((tf->protocol != ATA_PROT_DMA) &&
>> - (tf->protocol != ATA_PROT_NCQ))
>> + if (!ata_is_fpdma(tf->protocol))
>
> This is actually testing !DMA && !NCQ and an equivalent conversion but
> the rest aren't.
>
Yes.
>> diff --git a/drivers/ata/sata_nv.c b/drivers/ata/sata_nv.c
>> index 734f563..89e36aa 100644
>> --- a/drivers/ata/sata_nv.c
>> +++ b/drivers/ata/sata_nv.c
>> @@ -1407,7 +1407,7 @@ static void nv_adma_qc_prep(struct ata_queued_cmd *qc)
>> cpb->next_cpb_idx = 0;
>>
>> /* turn on NCQ flags for NCQ commands */
>> - if (qc->tf.protocol == ATA_PROT_NCQ)
>> + if (ata_is_fpdma(qc->tf.protocol))
>> ctl_flags |= NV_CPB_CTL_QUEUE | NV_CPB_CTL_FPDMA;
>
> And I don't know why testing NCQ or DMA would be safe for places like
> this.
>
Again, this driver cannot handle NCQ NON-DATA command, so it always has
to assume that NCQ _actually_ means FPDMA.
>> + ATA_PROT_FLAG_FPDMA = ATA_PROT_FLAG_NCQ | ATA_PROT_FLAG_DMA,
> ...
>> +static inline bool ata_is_fpdma(u8 prot)
>> +{
>> + return ata_prot_flags(prot) & ATA_PROT_FLAG_FPDMA;
>> +}
>
> ???
>
Yeah, strictly speaking there is no need for ATA_PROT_FLAG_FPDMA.
I'll be removing it if you insist.
Cheers,
Hannes
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