[U-Boot] [PATCH] bouncebuf: add feature to support buffer only available in DRAM

[Marek Vasut]

On 5/8/19 7:26 AM, Peng Fan wrote:
> Hi Kever,
> 
>> Subject: [PATCH] bouncebuf: add feature to support buffer only available in
>> DRAM
>>
>> Some DMA which inside peripheral controller can only access space in DRAM
>> area, the target address outside DRAM is not available.
>> eg. Rockchip MMC contrller's internal DMA can only access DRAM area.
>>
>> Add Kconfig option and driver for people who need it.
>>
>> Signed-off-by: Kever Yang <kever.yang at rock-chips.com>
>> ---
>>
>>  common/bouncebuf.c  | 9 +++++++++
>>  drivers/mmc/Kconfig | 6 ++++++
>>  2 files changed, 15 insertions(+)
>>
>> diff --git a/common/bouncebuf.c b/common/bouncebuf.c index
>> a7098e2caf..7ff2f488a4 100644
>> --- a/common/bouncebuf.c
>> +++ b/common/bouncebuf.c
>> @@ -10,6 +10,8 @@
>>  #include <errno.h>
>>  #include <bouncebuf.h>
>>
>> +DECLARE_GLOBAL_DATA_PTR;
>> +
>>  static int addr_aligned(struct bounce_buffer *state)  {
>>  	const ulong align_mask = ARCH_DMA_MINALIGN - 1; @@ -26,6 +28,13
>> @@ static int addr_aligned(struct bounce_buffer *state)
>>  		return 0;
>>  	}
>>
>> +#ifdef MMC_BUF_IN_DRAM
>> +	if (((ulong)state->user_buffer < CONFIG_SYS_SDRAM_BASE) ||
>> +	    ((ulong)state->user_buffer > gd->ram_top)) {
>> +		debug("Not support buffer address %p\n", state->user_buffer);
>> +		return 0;
>> +	}
>> +#endif
>>  	/* Aligned */
>>  	return 1;
>>  }
>> diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig index
>> c23299ea96..e852ee6175 100644
>> --- a/drivers/mmc/Kconfig
>> +++ b/drivers/mmc/Kconfig
>> @@ -671,6 +671,12 @@ config FSL_ESDHC
>>  	  This selects support for the eSDHC (enhanced secure digital host
>>  	  controller) found on numerous Freescale/NXP SoCs.
>>
>> +config MMC_BUF_IN_DRAM
>> +	bool "Only buffer in DRAM is available"
>> +	help
>> +	  This selects support those controller whose internal DMA can only
>> +	  access SDRAM spaces and other spaces are not available.
>> +
> 
> I think introduce a new GEN_BB_FORCE flags might be better, no need to
> introduce new kconfig entry, and it will be easier for others to use, if
> there are other controllers has same limitation.

Is the bounce buffer really the right place to put per-driver DMA
restrictions ?

-- 
Best regards,
Marek Vasut