[RFC 1/4] mmc: bcm2835_sdhci: use phys2bus macro when dma address is accessed

[Jaehoon Chung]

Hi Marek,

On 1/20/20 7:37 PM, Marek Szyprowski wrote:
> Hi Jaehoon,
> 
> On 20.01.2020 11:20, Jaehoon Chung wrote:
>> Use phys2bus macro when dma address is accessed.
>> After applied it, SDMA mode can be used.
>>
>> When thor download is used,
>> - Before : 1.8MB/s
>> - After : 7.23MB/s
>>
>> Signed-off-by: Jaehoon Chung <jh80.chung at samsung.com>
>> ---
>>   drivers/mmc/bcm2835_sdhci.c | 7 ++++++-
>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/bcm2835_sdhci.c b/drivers/mmc/bcm2835_sdhci.c
>> index 39c93db275..222ba22d66 100644
>> --- a/drivers/mmc/bcm2835_sdhci.c
>> +++ b/drivers/mmc/bcm2835_sdhci.c
>> @@ -46,6 +46,7 @@
>>   #include <asm/arch/mbox.h>
>>   #include <mach/sdhci.h>
>>   #include <mach/timer.h>
>> +#include <phys2bus.h>
>>   
>>   /* 400KHz is max freq for card ID etc. Use that as min */
>>   #define MIN_FREQ 400000
>> @@ -86,7 +87,11 @@ static inline void bcm2835_sdhci_raw_writel(struct sdhci_host *host, u32 val,
>>   			;
>>   	}
>>   
>> -	writel(val, host->ioaddr + reg);
>> +	if (reg == SDHCI_DMA_ADDRESS)
>> +		writel(phys_to_bus((unsigned long)val), host->ioaddr + reg);
>> +	else
>> +		writel(val, host->ioaddr + reg);
>> +
>>   	bcm_host->last_write = timer_get_us();
>>   }
> 
> It would be better to fix this directly in the place where writel with 
> SDHCI_DMA_ADDRESS is called:
> 
> simply change sdhci_writel(host, host->start_addr, SDHCI_DMA_ADDRESS) to 
> sdhci_writel(host, phys_to_bus(host->start_addr), SDHCI_DMA_ADDRESS);
> 
> In such case no if statement is the needed and phys_to_bus() is safe for 
> non-rpi users (it is identity in such case).
> 
> # git grep SDHCI_DMA_ADDRESS
> 
> shows 2 places where writel to SDHCI_DMA_ADDRESS is being done.

It's more reasonable than my patch. I will update it. Thanks.

Best Regards,
Jaehoon Chung

> 
> Best regards
>