From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH v2 2/5] spi: spi-ti-qspi: add mmap mode read support To: Mark Brown References: <1446545174-14193-1-git-send-email-vigneshr@ti.com> <1446545174-14193-3-git-send-email-vigneshr@ti.com> <20151104144112.GJ1717@sirena.org.uk> CC: Tony Lindgren , Michal Suchanek , Russell King , , , , , , From: Vignesh R Message-ID: <563AF429.1000406@ti.com> Date: Thu, 5 Nov 2015 11:46:09 +0530 MIME-Version: 1.0 In-Reply-To: <20151104144112.GJ1717@sirena.org.uk> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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