linux-kernel - Re: [PATCH 06/28] lib82596: move DMA allocation into the callers of i82596

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Message-ID: <20200901132905.GA11506@alpha.franken.de>
Date:   Tue, 1 Sep 2020 15:29:05 +0200
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     Christoph Hellwig <hch@....de>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Joonyoung Shim <jy0922.shim@...sung.com>,
        Seung-Woo Kim <sw0312.kim@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Ben Skeggs <bskeggs@...hat.com>,
        Pawel Osciak <pawel@...iak.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Matt Porter <mporter@...nel.crashing.org>,
        iommu@...ts.linux-foundation.org,
        Tom Lendacky <thomas.lendacky@....com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-ia64@...r.kernel.org, linux-mips@...r.kernel.org,
        linux-parisc@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        nouveau@...ts.freedesktop.org, netdev@...r.kernel.org,
        linux-nvme@...ts.infradead.org, linux-scsi@...r.kernel.org,
        linux-mm@...ck.org, alsa-devel@...a-project.org
Subject: Re: [PATCH 06/28] lib82596: move DMA allocation into the callers of
 i82596_probe

On Wed, Aug 19, 2020 at 08:55:33AM +0200, Christoph Hellwig wrote:
> This allows us to get rid of the LIB82596_DMA_ATTR defined and prepare
> for untangling the coherent vs non-coherent DMA allocation API.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
>  drivers/net/ethernet/i825xx/lasi_82596.c | 24 ++++++++++------
>  drivers/net/ethernet/i825xx/lib82596.c   | 36 ++++++++----------------
>  drivers/net/ethernet/i825xx/sni_82596.c  | 19 +++++++++----
>  3 files changed, 40 insertions(+), 39 deletions(-)
> 
> [...]
> diff --git a/drivers/net/ethernet/i825xx/sni_82596.c b/drivers/net/ethernet/i825xx/sni_82596.c
> index 22f5887578b2bd..e80e790ffbd4d4 100644
> --- a/drivers/net/ethernet/i825xx/sni_82596.c
> +++ b/drivers/net/ethernet/i825xx/sni_82596.c
> @@ -24,8 +24,6 @@
>  
>  static const char sni_82596_string[] = "snirm_82596";
>  
> -#define LIB82596_DMA_ATTR	0
> -
>  #define DMA_WBACK(priv, addr, len)     do { } while (0)
>  #define DMA_INV(priv, addr, len)       do { } while (0)
>  #define DMA_WBACK_INV(priv, addr, len) do { } while (0)
> @@ -134,10 +132,19 @@ static int sni_82596_probe(struct platform_device *dev)
>  	lp->ca = ca_addr;
>  	lp->mpu_port = mpu_addr;
>  
> +	lp->dma = dma_alloc_coherent(dev->dev.parent, sizeof(struct i596_dma),
> +				     &lp->dma_addr, GFP_KERNEL);

this needs to use &dev->dev as device argument otherwise I get a

WARNING: CPU: 0 PID: 1 at linux/kernel/dma/mapping.c:416 dma_alloc_attrs+0x64/0x98

(coherent_dma_mask is set correctly).

dev->dev.parent was correct when going from netdevice to underlying device,
but now allocation is done via platform_device probe. I wonder why this works
for parisc.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]