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

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Message-ID: <51F89F5E.2050605@ti.com>
Date:	Wed, 31 Jul 2013 10:53:42 +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 Wednesday 31 July 2013 10:00 AM, Joel Fernandes wrote:
> 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.

Okay, just drop the misleading comment then.

Regards,
Sekhar
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