linux-kernel - Re: [PATCH] DMA: PL330: Add dma api driver

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Message-ID: <AANLkTinAmHkVBii9nTZ5tNYU21whHy8awP55nGEc-8Tp@mail.gmail.com>
Date:	Mon, 17 May 2010 02:55:28 -0700
From:	Dan Williams <dan.j.williams@...el.com>
To:	Jassi Brar <jassi.brar@...sung.com>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	jy0922.shim@...sung.com, linus.ml.walleij@...il.com,
	maciej.sosnowski@...el.com, ben-linux@...ff.org
Subject: Re: [PATCH] DMA: PL330: Add dma api driver

Hi Jassi,

Looks good, one comment:

On Tue, May 11, 2010 at 10:23 PM, Jassi Brar <jassi.brar@...sung.com> wrote:
> Add DMA Engine API driver for the PL330 DMAC.
> This driver is supposed to be reusable by various
> platforms that have one or more PL330 DMACs.
> Atm, DMA_SLAVE and DMA_MEMCPY capabilities have been
> implemented.
>
> Signed-off-by: Jassi Brar <jassi.brar@...sung.com>
[..]
> +static void dma_pl330_rqcb(void *token, enum pl330_op_err err)
> +{
> +       struct dma_pl330_desc *desc = token;
> +       struct dma_pl330_chan *pch = desc->pchan;
> +       unsigned long flags;
> +
> +       /* If desc aborted */
> +       if (!pch)
> +               return;
> +
> +       spin_lock_irqsave(&pch->lock, flags);
> +
> +       desc->status = DONE;
> +
> +       spin_unlock_irqrestore(&pch->lock, flags);

I don't think you need the lock here.  Assigning an integer is atomic,
and you reschedule the tasklet.

Since this patch depends on the generic bits in Russell's tree I need
to wait until after the ARM tree is pulled to take it through the dma
tree.  So, for now...

Acked-by: Dan Williams <dan.j.williams@...el.com>
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