From mboxrd@z Thu Jan  1 00:00:00 1970
From: b32955@freescale.com (Huang Shijie)
Date: Thu, 19 Jan 2012 17:31:19 +0800
Subject: [PATCH 06/10] MXS-DMA : add more flags for MXS-DMA
In-Reply-To: <20120119090238.GU1068@n2100.arm.linux.org.uk>
References: <1326953767-24155-1-git-send-email-b32955@freescale.com>
 <1326953767-24155-7-git-send-email-b32955@freescale.com>
 <20120119090238.GU1068@n2100.arm.linux.org.uk>
Message-ID: <4F17E2E7.2080300@freescale.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

hi,
> Err, the 'flags' argument to device_prep_slave_sg() is supposed to be
> from the set of enum dma_ctrl_flags.  What this means is that your
> MXS_DMA_F_APPEND is equivalent to DMA_PREP_INTERRUPT, and
> MXS_DMA_F_WAIT4END is equivalent to DMA_CTRL_ACK.
>
thanks a lot.
I will reuse the dma_ctrl_flags in the next version.
> What this does is make your drivers completely dependent on your DMA
> engine implementation.  That's not a good idea when devices get
> reused in different SoCs.
>
Frankly speaking, the APBH-DMA is more coupled with the GPMI  then any 
other modules.
In the MX6Q, the GPMI is the ONLY user of APBH-DMA.
You even can see the NAND_LOCK bit in the DMA command structure which is 
only used by the GPMI
NAND controller,.


To Shawn & Wolfram:
    thanks very much for your comments.

Best Regards
Huang Shijie

> If you need to supply extra flags which aren't in the dma_ctrl_flags,
> at least make sure that they're using different bits.  For bonus points,
> also have your driver_check_  the DMA engine it's connected to before
> it passes these flags.
>