linux-kernel - Re: [PATCH 13/32] dmaengine: ste_dma40: Calculate number of logical channels from physical ones

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Date:	Thu, 25 Apr 2013 14:51:51 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Lee Jones <lee.jones@...aro.org>
Cc:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Arnd Bergmann <arnd@...db.de>,
	Linus WALLEIJ <linus.walleij@...ricsson.com>,
	Vinod Koul <vinod.koul@...el.com>, Dan Williams <djbw@...com>,
	Per Forlin <per.forlin@...ricsson.com>,
	Rabin Vincent <rabin@....in>
Subject: Re: [PATCH 13/32] dmaengine: ste_dma40: Calculate number of logical
 channels from physical ones

On Thu, Apr 25, 2013 at 11:29 AM, Lee Jones <lee.jones@...aro.org> wrote:
> On Thu, 25 Apr 2013, Linus Walleij wrote:
>
>> On Thu, Apr 18, 2013 at 12:11 PM, Lee Jones <lee.jones@...aro.org> wrote:
>>
>> > This change will cost ~25KB of memory, but it's worth the trade-off,
>> > as it removes a great deal of overhead. It means that instead of only
>> > allocating memory for the logical channels in use, it does so for all
>> > available ones, which is 32 per physical channel. However, this now
>> > means we can remove some platform data and we don't have to worry
>> > about adding vendor specific variables to Device Tree.
>> >
>> > Cc: Vinod Koul <vinod.koul@...el.com>
>> > Cc: Dan Williams <djbw@...com>
>> > Cc: Per Forlin <per.forlin@...ricsson.com>
>> > Cc: Rabin Vincent <rabin@....in>
>> > Signed-off-by: Lee Jones <lee.jones@...aro.org>
>>
>> (...)
>> >  static struct stedma40_platform_data dma40_plat_data = {
>> > -       .dev_len = DB8500_DMA_NR_DEV,
>>
>> So that was set to 64 in the platform...
>>
>> > -       /* Count the number of logical channels in use */
>> > -       for (i = 0; i < plat_data->dev_len; i++)
>> > -               if (plat_data->dev_rx[i] != 0)
>> > -                       num_log_chans++;
>> > -
>> > -       for (i = 0; i < plat_data->dev_len; i++)
>> > -               if (plat_data->dev_tx[i] != 0)
>> > -                       num_log_chans++;
>>
>> And I guess this code snippet made it go down to <= 32 all the time,
>> correct?
>
> However many were described in dma40_[rx|tx]_map, yes.

OK how fragile, but definately not your fault.
Acked-by: Linus Walleij <linus.walleij@...aro.org>

Yours,
Linus Walleij
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