linux-kernel - Re: [PATCH 3/9] ARM: edma: Add function to manually trigger an EDMA channel

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Message-ID: <51F74CAD.3040604@ti.com>
Date:	Tue, 30 Jul 2013 10:48:37 +0530
From:	Sekhar Nori <nsekhar@...com>
To:	Joel Fernandes <joelf@...com>
CC:	Tony Lindgren <tony@...mide.com>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Sricharan R <r.sricharan@...com>,
	Rajendra Nayak <rnayak@...com>,
	Lokesh Vutla <lokeshvutla@...com>,
	Matt Porter <matt@...orter.com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Herring <rob.herring@...xeda.com>,
	Vinod Koul <vinod.koul@...el.com>, Dan Williams <djbw@...com>,
	Mark Brown <broonie@...aro.org>,
	Benoit Cousson <benoit.cousson@...aro.org>,
	Russell King <linux@....linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>, Olof Johansson <olof@...om.net>,
	Balaji TK <balajitk@...com>,
	Gururaja Hebbar <gururaja.hebbar@...com>,
	Chris Ball <cjb@...top.org>,
	Jason Kridner <jkridner@...gleboard.org>,
	Linux OMAP List <linux-omap@...r.kernel.org>,
	Linux ARM Kernel List <linux-arm-kernel@...ts.infradead.org>,
	Linux DaVinci Kernel List 
	<davinci-linux-open-source@...ux.davincidsp.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux MMC List <linux-mmc@...r.kernel.org>
Subject: Re: [PATCH 3/9] ARM: edma: Add function to manually trigger an EDMA
 channel

On Monday 29 July 2013 06:59 PM, Joel Fernandes wrote:
> Manual trigger for events missed as a result of splitting a
> scatter gather list and DMA'ing it in batches. Add a helper
> function to trigger a channel incase any such events are missed.
> 
> Signed-off-by: Joel Fernandes <joelf@...com>
> ---
>  arch/arm/common/edma.c             |   21 +++++++++++++++++++++
>  include/linux/platform_data/edma.h |    2 ++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/arch/arm/common/edma.c b/arch/arm/common/edma.c
> index 3567ba1..10995b2 100644
> --- a/arch/arm/common/edma.c
> +++ b/arch/arm/common/edma.c
> @@ -1236,6 +1236,27 @@ void edma_resume(unsigned channel)
>  }
>  EXPORT_SYMBOL(edma_resume);
>  
> +int edma_manual_trigger(unsigned channel)

edma_trigger_channel() maybe? Brings consistency with
edma_alloc_channel() edma_free_channel() etc.

> +{
> +	unsigned ctlr;
> +	int j;
> +	unsigned int mask;
> +
> +	ctlr = EDMA_CTLR(channel);
> +	channel = EDMA_CHAN_SLOT(channel);
> +	mask = BIT(channel & 0x1f);
> +
> +	j = channel >> 5;
> +
> +	/* EDMA channels without event association */

May be actually check for no-event association before you trigger in
software? You can do that by looking at unused channel list, no?

> +	edma_shadow0_write_array(ctlr, SH_ESR, j, mask);

edma_shadow0_write_array(ctlr, SH_ESR, channel >> 5, mask) is no less
readable, but I leave it to you.

Thanks,
Sekhar

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