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

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Message-ID: <20130422101133.GG3432@gmail.com>
Date:	Mon, 22 Apr 2013 11:11:33 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Vinod Koul <vinod.koul@...el.com>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	arnd@...db.de, linus.walleij@...ricsson.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 Mon, 22 Apr 2013, Vinod Koul wrote:

> On Thu, Apr 18, 2013 at 11:11:55AM +0100, Lee Jones 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>
> > ---
> >  arch/arm/mach-ux500/devices-db8500.c        |    1 -
> >  drivers/dma/ste_dma40.c                     |   16 ++++++----------
> >  include/linux/platform_data/dma-ste-dma40.h |    2 --
> >  3 files changed, 6 insertions(+), 13 deletions(-)
> > 
> > diff --git a/arch/arm/mach-ux500/devices-db8500.c b/arch/arm/mach-ux500/devices-db8500.c
> > index 03efd4c1..2fcb8c2 100644
> > --- a/arch/arm/mach-ux500/devices-db8500.c
> > +++ b/arch/arm/mach-ux500/devices-db8500.c
> > @@ -121,7 +121,6 @@ static const dma_addr_t dma40_rx_map[DB8500_DMA_NR_DEV] = {
> >  };
> >  
> >  static struct stedma40_platform_data dma40_plat_data = {
> > -	.dev_len = DB8500_DMA_NR_DEV,
> >  	.dev_rx = dma40_rx_map,
> >  	.dev_tx = dma40_tx_map,
> >  	.disabled_channels = {-1},
> > diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
> > index 7b451b2..a39ef74 100644
> > --- a/drivers/dma/ste_dma40.c
> > +++ b/drivers/dma/ste_dma40.c
> > @@ -45,6 +45,9 @@
> >  #define D40_LCLA_LINK_PER_EVENT_GRP 128
> >  #define D40_LCLA_END D40_LCLA_LINK_PER_EVENT_GRP
> >  
> > +/* Max number of logical channels per physical channel */
> > +#define D40_MAX_LOG_CHAN_PER_PHY 32
> > +
> >  /* Attempts before giving up to trying to get pages that are aligned */
> >  #define MAX_LCLA_ALLOC_ATTEMPTS 256
> >  
> > @@ -3197,6 +3200,8 @@ static struct d40_base * __init d40_hw_detect_init(struct platform_device *pdev)
> >  	else
> >  		num_phy_chans = 4 * (readl(virtbase + D40_DREG_ICFG) & 0x7) + 4;
> >  
> > +	num_log_chans = num_phy_chans * D40_MAX_LOG_CHAN_PER_PHY;
> > +
> >  	dev_info(&pdev->dev, "hardware revision: %d @ 0x%x with %d physical channels\n",
> >  		 rev, res->start, num_phy_chans);
> >  
> > @@ -3206,15 +3211,6 @@ static struct d40_base * __init d40_hw_detect_init(struct platform_device *pdev)
> >  		goto failure;
> >  	}
> >  
> > -	/* 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++;
> > -
> >  	base = kzalloc(ALIGN(sizeof(struct d40_base), 4) +
> >  		       (num_phy_chans + num_log_chans + ARRAY_SIZE(dma40_memcpy_channels)) *
> >  		       sizeof(struct d40_chan), GFP_KERNEL);
> > @@ -3282,7 +3278,7 @@ static struct d40_base * __init d40_hw_detect_init(struct platform_device *pdev)
> >  		 * The max number of logical channels are event lines for all
> >  		 * src devices and dst devices
> >  		 */
> > -		base->lookup_log_chans = kzalloc(plat_data->dev_len * 2 *
> > +		base->lookup_log_chans = kzalloc(num_log_chans *
> you could have used devm_ helper for this.

I'll convert the entire driver over to devm_ in a latter patch.

> Acked-by: Vinod Koul <vnod.koul@...el.com>

Thanks. 

-- 
Lee Jones
Linaro ST-Ericsson Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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