[PATCH 4/4] mtd: spi-nor: aspeed: use command mode for reads

[Cédric Le Goater]

On 04/20/2017 03:58 PM, Marek Vasut wrote:
> On 04/20/2017 03:53 PM, Cédric Le Goater wrote:
>> On 04/20/2017 03:31 PM, Marek Vasut wrote:
>>> On 04/20/2017 01:56 PM, Cédric Le Goater wrote:
>>>> When reading flash contents, try to use the "command mode" if the AHB
>>>> window configured for the flash module is big enough. Else, just fall
>>>> back to the "user mode" to perform the read.
>>>>
>>>> Signed-off-by: Cédric Le Goater <clg at kaod.org>
>>>> ---
>>>>
>>>>  Changes since initial version :
>>>>
>>>>  - rebased on current patchset which removed DMA support
>>>>
>>>>  drivers/mtd/spi-nor/aspeed-smc.c | 27 ++++++++++++++++++++++++++-
>>>>  1 file changed, 26 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/mtd/spi-nor/aspeed-smc.c b/drivers/mtd/spi-nor/aspeed-smc.c
>>>> index 60c020482946..43015aec4557 100644
>>>> --- a/drivers/mtd/spi-nor/aspeed-smc.c
>>>> +++ b/drivers/mtd/spi-nor/aspeed-smc.c
>>>> @@ -394,6 +394,31 @@ static ssize_t aspeed_smc_read_user(struct spi_nor *nor, loff_t from,
>>>>  
>>>>  	aspeed_smc_read_from_ahb(read_buf, chip->ahb_base, len);
>>>>  	aspeed_smc_stop_user(nor);
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static ssize_t aspeed_smc_read(struct spi_nor *nor, loff_t from, size_t len,
>>>> +			       u_char *read_buf)
>>>> +{
>>>> +	struct aspeed_smc_chip *chip = nor->priv;
>>>> +
>>>> +	/*
>>>> +	 * The AHB window configured for the chip is too small for the
>>>> +	 * read offset. Use the "User mode" of the controller to
>>>> +	 * perform the read.
>>>> +	 */
>>>> +	if (from >= chip->ahb_window_size) {
>>>> +		aspeed_smc_read_user(nor, from, len, read_buf);
>>>> +		goto out;
>>>
>>> What about turning this into dumb if () {} else {} and dropping the goto ?
>>
>> yes, well, this is because I have other patches adding DMAs :
>>
>> 	https://github.com/legoater/linux/commit/6880924dc2cf7a47c446a708df528b72d9bf9134#diff-e466368d609006970aab53a7b840221fR575
>>
>> but as of today, the benefits in speed are to be proven and the current 
>> implementation does not support vmalloc'ed buffers. So I can drop the 
>> goto without too much regrets (if you insist :)
> 
> Nah, if you have further plans with this code, I don't mind either way.
> 

OK let's keep that way.

Do you think we can merge these four patches in the next window ? 

Thanks,

C.