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SubjectRe: [PATCH] dmaengine: ti: omap-dma: Configure LCH_TYPE for OMAP1
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On 17/12/2018 21.16, Aaro Koskinen wrote:
> On Thu, Nov 22, 2018 at 03:12:36PM +0000, Russell King - ARM Linux wrote:
>> Also we can't deal with the omap_set_dma_dest_burst_mode() setting -
>> DMAengine always uses a 64 byte burst, but udc wants a smaller burst
>> setting. Does this matter?
>
> Looking at OMAP1 docs, it seems it supports only 16 bytes. Then checking
> DMAengine code, I don't think these CSDP bit values are not valid
> for OMAP1:
>
> CSDP_SRC_BURST_1 = 0 << 7,
> CSDP_SRC_BURST_16 = 1 << 7,
> CSDP_SRC_BURST_32 = 2 << 7,
> CSDP_SRC_BURST_64 = 3 << 7,
>
> From TI SPRU674 document, pages 50-51:
>
> 0 single access (no burst)
> 1 single access (no burst)
> 2 burst 4

In omap1510 it is 4 x data_type
In omap1610/1710 it is 4 x data_type (only data_type == 32bit is supported)
From omap2420+ 32 bytes (8x32bit/4x64bit)

So for OMAP1 we need to have different handling of the burst:
only enable if data_type is 32bit.

> 3 reserved (do not use this setting)
>
> So if CSDP_SRC_BURST_64 (3) gets programmed OMAP1, I wonder what is the
> end result, no burst or burst 4...
>
> A.
>

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

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