Re: [PATCH] dmaengine: delete redundant chan_id and chancntinitialization in dma drivers

[Jassi Brar]

On Fri, Sep 16, 2011 at 3:13 PM, Barry Song <Baohua.Song@xxxxxxx> wrote:
> dma_async_device_register will re-init chan_id and chancnt,
> so whatever chan_id and chancnt are set in drivers, they will
> be re-written by dma_async_device_register.
>
> Cc: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
> Cc: Viresh Kumar <viresh.kumar@xxxxxx>
> Cc: Vinod Koul <vinod.koul@xxxxxxxxx>
> Cc: Piotr Ziecik <kosmo@xxxxxxxxxxxx>
> Cc: Yong Wang <yong.y.wang@xxxxxxxxx>
> Cc: Jaswinder Singh <jassi.brar@xxxxxxxxxxx>
> Cc: Pelagicore AB <info@xxxxxxxxxxxxxx>
> Signed-off-by: Barry Song <Baohua.Song@xxxxxxx>
> ---
> Âdrivers/dma/at_hdmac.c   Â|  Â5 ++---
> Âdrivers/dma/dw_dmac.c    |  Â5 ++---
> Âdrivers/dma/intel_mid_dma.c | Â Â2 --
> Âdrivers/dma/mpc512x_dma.c  |  Â1 -
> Âdrivers/dma/pch_dma.c    |  Â2 --
> Âdrivers/dma/pl330.c     |  Â2 --
> Âdrivers/dma/timb_dma.c   Â|  Â3 +--

Apparently ....

drivers/dma/ppc4xx/adma.c
drivers/dma/ipu/ipu_idmac.c
       still write to chan_id.

drivers/dma/amba-pl08x.c
drivers/dma/fsldma.c
drivers/dma/ioat/dma_v2.c
drivers/dma/ioat/dma.c
drivers/dma/mpc512x_dma.c
drivers/dma/shdma.c
       still write to chancnt

Most of them are simply a matter of removal, but some seem
like really depending upon setting them(?)

Anyways, even after you modify those as well, chan_id and chancnt
are rendered overstaying guests in dmaengine core. Because chan_id
of each channel would be _precisely_ the order in which the
_dmac-driver_ added the channel to the 'channels' list.

So if their values are _always_ gonna be just contiguously incrementing
why need variables for that in the dmaengine api?
Dmac drivers could use local variables for that.

OTOH, why not chan_id be left solely for use by dmac drivers read by the
dmaengine only to create sysfs entries ?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/