Re: [PATCH net-next v3 2/7] dma: avoid redundant calls for sync operations

[Robin Murphy]

On 19/02/2024 12:49 pm, Alexander Lobakin wrote:
> From: Robin Murphy <robin.murphy@xxxxxxx>
> Date: Wed, 14 Feb 2024 17:55:23 +0000
>
> > On 2024-02-14 4:21 pm, Alexander Lobakin wrote:
>
> [...]
>
> > > +        /*
> > > +         * Synchronization is not possible when none of DMA sync ops
> > > +         * is set. This check precedes the below one as it disables
> > > +         * the synchronization unconditionally.
> > > +         */
> > > +        dev->dma_skip_sync = true;
> > > +    else if (ops->flags & DMA_F_CAN_SKIP_SYNC)
> >
> > Personally I'd combine this into the dma-direct condition.
>
> Please read the code comment a couple lines above :D

And my point is that that logic is not actually useful, since it would 
be nonsensical for ops to set DMA_F_CAN_SKIP_SYNC if they don't even 
implement sync ops anyway.

If the intent of DMA_F_CAN_SKIP_SYNC is to mean "behaves like 
dma-direct", then "if (dma_map_direct(...) || ops->flags & 
DMA_F_CAN_SKIP_SYNC)" is an entirely logical and expected condition.

Thanks,
Robin.