Subject: Re: linux-next: manual merge of the dmaengine tree with the dmaengine-fixes tree

From: Stephen Rothwell <[email-masked]>
Date: Tue, 15 Dec 2020 06:58:31 +1100

Hi all,

On Thu, 19 Nov 2020 14:29:15 +1100 Stephen Rothwell <[email-masked]> wrote:
>
> Today's linux-next merge of the dmaengine tree got a conflict in:
> 
>   drivers/dma/idxd/submit.c
> 
> between commit:
> 
>   8326be9f1c0b ("dmaengine: idxd: fix mapping of portal size")
> 
> from the dmaengine-fixes tree and commit:
> 
>   8e50d392652f ("dmaengine: idxd: Add shared workqueue support")
> 
> from the dmaengine tree.
> 
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
> 
> diff --cc drivers/dma/idxd/submit.c
> index 417048e3c42a,efca5d8468a6..000000000000
> --- a/drivers/dma/idxd/submit.c
> +++ b/drivers/dma/idxd/submit.c
> @@@ -74,14 -86,27 +86,27 @@@ int idxd_submit_desc(struct idxd_wq *wq
>   	if (idxd->state != IDXD_DEV_ENABLED)
>   		return -EIO;
>   
> - 	portal = wq->dportal;
>  -	portal = wq->portal + idxd_get_wq_portal_offset(IDXD_PORTAL_LIMITED);
> ++	portal = wq->portal;
> + 
>   	/*
> - 	 * The wmb() flushes writes to coherent DMA data before possibly
> - 	 * triggering a DMA read. The wmb() is necessary even on UP because
> - 	 * the recipient is a device.
> + 	 * The wmb() flushes writes to coherent DMA data before
> + 	 * possibly triggering a DMA read. The wmb() is necessary
> + 	 * even on UP because the recipient is a device.
>   	 */
>   	wmb();
> - 	iosubmit_cmds512(portal, desc->hw, 1);
> + 	if (wq_dedicated(wq)) {
> + 		iosubmit_cmds512(portal, desc->hw, 1);
> + 	} else {
> + 		/*
> + 		 * It's not likely that we would receive queue full rejection
> + 		 * since the descriptor allocation gates at wq size. If we
> + 		 * receive a -EAGAIN, that means something went wrong such as the
> + 		 * device is not accepting descriptor at all.
> + 		 */
> + 		rc = enqcmds(portal, desc->hw);
> + 		if (rc < 0)
> + 			return rc;
> + 	}
>   
>   	/*
>   	 * Pending the descriptor to the lockless list for the irq_entry

Just a reminder that this conflict still exists.  Commit 8326be9f1c0b
is now in Linus' tree.

-- 
Cheers,
Stephen Rothwell