[PATCH v2 2/5] spi: spi-ti-qspi: add mmap mode read support

Vignesh R
2015-11-05T06:16:09Z

On 11/04/2015 08:11 PM, Mark Brown wrote:
> On Tue, Nov 03, 2015 at 03:36:11PM +0530, Vignesh R wrote:
>
>> + ti_qspi_enable_memory_map(spi);
>> + ti_qspi_setup_mmap_read(spi, read_opcode, addr_width,
>> + dummy_bytes);
>> + memcpy_fromio(buf, qspi->mmap_base + from, len);
>> + *retlen = len;
>> + ti_qspi_disable_memory_map(spi);
>
> We'll be constantly enabling and disabling memory mapping with this.
> I'm not sure that's a meaningful cost given that it doesn't actually
> remap anything but rather just switches hardware modes, we can always
> optimise it later if it is.
>

Hmm, I will move the ti_qspi_disable_memory_map() call to
ti_qspi_start_transfer_one(), so that mmap mode is disabled only when
normal SPI bus transfer is requested. Further, "mmap_enabled" status
flag can be used to determine whether mode switch is required or not.
This should help to overcome enabling and disabling memory mapping
between successive mmap read requests.

--
Regards
Vignesh