linux-kernel - Re: [PATCH v5 2/2] DW DMAC: add multi-block property to device tree

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Message-ID: <1480002728.20074.15.camel@linux.intel.com>
Date:   Thu, 24 Nov 2016 17:52:08 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        devicetree@...r.kernel.org
Cc:     robh+dt@...nel.org, mark.rutland@....com,
        linux-kernel@...r.kernel.org, vinod.koul@...el.com,
        dmaengine@...r.kernel.org, arnd@...db.de,
        linux-snps-arc@...ts.infradead.org, vireshk@...nel.org,
        shiraz.linux.kernel@...il.com, christian.ruppert@...tech.com
Subject: Re: [PATCH v5 2/2] DW DMAC: add multi-block property to device tree

On Thu, 2016-11-24 at 18:04 +0300, Eugeniy Paltsev wrote:
> Several versions of DW DMAC have multi block transfers hardware
> support. Hardware support of multi block transfers is disabled
> by default if we use DT to configure DMAC and software emulation
> of multi block transfers used instead.
> Add multi-block property, so it is possible to enable hardware
> multi block transfers (if present) via DT.
> 
> Switch from per device is_nollp variable to multi_block array
> to be able enable/disable multi block transfers separately per
> channel.

Thanks for an update. Basically I'm fine with this one.

So, we still have question about autoconfiguration in SPEAr SoCs, and
your ARC SoC but it's a different story. I would expect once you will
clarify it.

Another one is minor listed below, otherwise

Acked-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>

> --- a/drivers/dma/dw/platform.c
> +++ b/drivers/dma/dw/platform.c
> @@ -102,7 +102,7 @@ dw_dma_parse_dt(struct platform_device *pdev)
>  {
>  	struct device_node *np = pdev->dev.of_node;
>  	struct dw_dma_platform_data *pdata;
> -	u32 tmp, arr[DW_DMA_MAX_NR_MASTERS];
> +	u32 tmp, arr[DW_DMA_MAX_NR_MASTERS],
> chan[DW_DMA_MAX_NR_CHANNELS];

chan here will confuse people...

> @@ -152,6 +154,11 @@ dw_dma_parse_dt(struct platform_device *pdev)
>  			pdata->data_width[tmp] = BIT(arr[tmp] &
> 0x07);
>  	}
>  
> +	if (!of_property_read_u32_array(np, "multi-block", chan,
> nr_channels)) {
> +		for (tmp = 0; tmp < nr_channels; tmp++)
> +			pdata->multi_block[tmp] = chan[tmp];

...mb (as short of multi-block) would suit better.

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy