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

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Date:	Tue, 30 Jul 2013 23:30:10 -0500
From:	Joel Fernandes <joelf@...com>
To:	Sekhar Nori <nsekhar@...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 07/30/2013 12:18 AM, Sekhar Nori wrote:
> 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.

Ok, sure.

> 
>> +{
>> +	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?

But, we want to trigger whether there is event association or not in
this function. For ex, MMC has event associated but still this function
is used to trigger event for it.

> 
>> +	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.

Sure that's more readable, will changed it to that.

Thanks,

-Joel

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