[U-Boot] [PATCH V2] i.MX: fsl_esdhc: allow use with cache enabled.

[Stefano Babic <sbabic@denx.de>]

On 09/05/2012 01:31, Eric Nelson wrote:
> Thanks Andy,
> 
> On 05/08/2012 03:59 PM, Andy Fleming wrote:
>>> --- a/drivers/mmc/fsl_esdhc.c
>>> +++ b/drivers/mmc/fsl_esdhc.c
>>> @@ -190,6 +190,10 @@ static int esdhc_setup_data(struct mmc *mmc,
>>> struct mmc_data *data)
>>>                 esdhc_clrsetbits32(&regs->wml, WML_RD_WML_MASK,
>>> wml_value);
>>>                 esdhc_write32(&regs->dsaddr, (u32)data->dest);
>>>         } else {
>>> +               flush_dcache_range((ulong)data->src,
>>> +                                  (ulong)data->src+data->blocks
>>> +                                        *data->blocksize);
>>> +
>>
>>
>> This still won't work. I don't believe this is implemented at all on
>> the FSL PowerPC parts that use this controller.
>>
>> At the very least, it needs to be protected by an ifdef.
>>
> 
> It seems more generally useful to implement a PowerPC cache layer
> than to instrument each driver that supports cache.

Some PowerPC (MPC86xx,  arch/powerpc/cpu/mpc86xx/cache.S) have this
layer, some other not. This driver is used by MPC85xx and
flush_dcache_range is not implemented. The reason is that this SOC  uses
its internal snooping mechanism and does not need to explicitely flush
the buffers in the drivers.

The problem with an #ifdef is that it is not very generic - we should
add some #if (defined(CONFIG_MX51) || defined(CONFIG_MX53) || ...
and update the driver for each new SOCs. I think also that maybe the
best way is to add an empty flush_dcache_range() to the MPC85xx, maybe
as weak function.

Best regards,
Stefano

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