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

From	Vignesh R <vigneshr@ti.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 2/5] spi: spi-ti-qspi: add mmap mode read support
Date	2015-11-05 07:20 +0100
Message-ID	<qrm3U-2Ut-5@gated-at.bofh.it> (permalink)
References	<qqGHo-1jJ-7@gated-at.bofh.it> <qqGHo-1jJ-5@gated-at.bofh.it> <qr7xU-1HX-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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
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[PATCH v2 2/5] spi: spi-ti-qspi: add mmap mode read support Vignesh R <vigneshr@ti.com> - 2015-11-03 11:10 +0100
  Re: [PATCH v2 2/5] spi: spi-ti-qspi: add mmap mode read support Mark Brown <broonie@kernel.org> - 2015-11-04 15:50 +0100
    Re: [PATCH v2 2/5] spi: spi-ti-qspi: add mmap mode read support Vignesh R <vigneshr@ti.com> - 2015-11-05 07:20 +0100

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