linux-kernel - Re: [PATCH 2/2] Add COH 901 318 DMA driver platform config for U300 v3

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Date:	Thu, 29 Oct 2009 13:39:27 +0100
From:	Linus Walleij <linus.ml.walleij@...il.com>
To:	Dan Williams <dan.j.williams@...el.com>
Cc:	Linus Walleij <linus.walleij@...ricsson.com>,
	Maciej Sosnowski <maciej.sosnowski@...el.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/2] Add COH 901 318 DMA driver platform config for U300 
	v3

2009/10/28 Dan Williams <dan.j.williams@...el.com>:

> On Wed, Oct 28, 2009 at 8:19 AM, Linus Walleij
> <linus.walleij@...ricsson.com> wrote:
> [..]
>> +#define flags_memcpy_config (COH901318_CX_CFG_CH_DISABLE | \
>> +                       COH901318_CX_CFG_RM_MEMORY_TO_MEMORY | \
>> +                       COH901318_CX_CFG_LCR_DISABLE | \
>> +                       COH901318_CX_CFG_TC_IRQ_ENABLE | \
>> +                       COH901318_CX_CFG_BE_IRQ_ENABLE)
>> +#define flags_memcpy_lli_chained (COH901318_CX_CTRL_TC_ENABLE | \
>> +                       COH901318_CX_CTRL_BURST_COUNT_32_BYTES | \
>> +                       COH901318_CX_CTRL_SRC_BUS_SIZE_32_BITS | \
>> +                       COH901318_CX_CTRL_SRC_ADDR_INC_ENABLE | \
>> +                       COH901318_CX_CTRL_DST_BUS_SIZE_32_BITS | \
>> +                       COH901318_CX_CTRL_DST_ADDR_INC_ENABLE | \
>> +                       COH901318_CX_CTRL_MASTER_MODE_M1RW | \
>> +                       COH901318_CX_CTRL_TCP_DISABLE | \
>> +                       COH901318_CX_CTRL_TC_IRQ_DISABLE | \
>> +                       COH901318_CX_CTRL_HSP_DISABLE | \
>> +                       COH901318_CX_CTRL_HSS_DISABLE | \
>> +                       COH901318_CX_CTRL_DDMA_LEGACY | \
>> +                       COH901318_CX_CTRL_PRDD_SOURCE)
>> +#define flags_memcpy_lli (COH901318_CX_CTRL_TC_ENABLE | \
>> +                       COH901318_CX_CTRL_BURST_COUNT_32_BYTES | \
>> +                       COH901318_CX_CTRL_SRC_BUS_SIZE_32_BITS | \
>> +                       COH901318_CX_CTRL_SRC_ADDR_INC_ENABLE | \
>> +                       COH901318_CX_CTRL_DST_BUS_SIZE_32_BITS | \
>> +                       COH901318_CX_CTRL_DST_ADDR_INC_ENABLE | \
>> +                       COH901318_CX_CTRL_MASTER_MODE_M1RW | \
>> +                       COH901318_CX_CTRL_TCP_DISABLE | \
>> +                       COH901318_CX_CTRL_TC_IRQ_DISABLE | \
>> +                       COH901318_CX_CTRL_HSP_DISABLE | \
>> +                       COH901318_CX_CTRL_HSS_DISABLE | \
>> +                       COH901318_CX_CTRL_DDMA_LEGACY | \
>> +                       COH901318_CX_CTRL_PRDD_SOURCE)
>> +#define flags_memcpy_lli_last (COH901318_CX_CTRL_TC_ENABLE | \
>> +                       COH901318_CX_CTRL_BURST_COUNT_32_BYTES | \
>> +                       COH901318_CX_CTRL_SRC_BUS_SIZE_32_BITS | \
>> +                       COH901318_CX_CTRL_SRC_ADDR_INC_ENABLE | \
>> +                       COH901318_CX_CTRL_DST_BUS_SIZE_32_BITS | \
>> +                       COH901318_CX_CTRL_DST_ADDR_INC_ENABLE | \
>> +                       COH901318_CX_CTRL_MASTER_MODE_M1RW | \
>> +                       COH901318_CX_CTRL_TCP_DISABLE | \
>> +                       COH901318_CX_CTRL_TC_IRQ_ENABLE | \
>> +                       COH901318_CX_CTRL_HSP_DISABLE | \
>> +                       COH901318_CX_CTRL_HSS_DISABLE | \
>> +                       COH901318_CX_CTRL_DDMA_LEGACY | \
>> +                       COH901318_CX_CTRL_PRDD_SOURCE)
>
> You go through the hassle of defining these flag combination sets...
>
>> +               .param.config = COH901318_CX_CFG_CH_DISABLE |
>> +                               COH901318_CX_CFG_RM_MEMORY_TO_PRIMARY |
>> +                               COH901318_CX_CFG_LCR_DISABLE |
>> +                               COH901318_CX_CFG_TC_IRQ_ENABLE |
>> +                               COH901318_CX_CFG_BE_IRQ_ENABLE,
>
> ...but then don't use them to cut down on the line count in the
> definition of these parameters?

We do, look further below:

+       {
+               .number = U300_DMA_GENERAL_PURPOSE_0,
+               .name = "GENERAL 00",
+               .priority_high = 0,
+
+               .param.config = flags_memcpy_config,
+               .param.ctrl_lli_chained = flags_memcpy_lli_chained,
+               .param.ctrl_lli = flags_memcpy_lli,
+               .param.ctrl_lli_last = flags_memcpy_lli_last,
+       },

Only the general purpose channels support memcpy and these are all set
up the same way (for accelerating memcpy() operations).

The rest of the channels are, mem -> io, io -> mem, io -> io and the io
(device DMA) configurations are individual and varies greatly with
hardware. For some currently unused hardware we haven't even defined
the proper flags yet, and e.g. changing the burst size of an individual
channel without affecting the rest is something a developer is very
likely to do.

Linus Walleij
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