From mboxrd@z Thu Jan 1 00:00:00 1970 From: anton.bondarenko.sama@gmail.com (Anton Bondarenko) Date: Wed, 21 Oct 2015 01:08:17 +0200 Subject: [PATCH v2 5/8] spi: imx: Add support for loopback for ECSPI controllers In-Reply-To: <20151008092827.GB6101@shlinux2> References: <20150930084219.GE2709@shlinux2> <04376A3D786BD947B28569C998A374A62E280E0F@NA-MBX-02.mgc.mentorg.com> <20151008092827.GB6101@shlinux2> Message-ID: <5626C961.7070009@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 08.10.2015 11:28, Robin Gong wrote: > On Thu, Oct 01, 2015 at 12:16:49AM +0000, Bondarenko, Anton wrote: >> On 30.09.2015 10:42, Robin Gong wrote: >>> On Fri, Sep 25, 2015 at 07:57:12PM +0200, Anton Bondarenko wrote: >>>> @@ -370,8 +374,12 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx, >>>> if (config->mode & SPI_CS_HIGH) >>>> cfg |= MX51_ECSPI_CONFIG_SSBPOL(config->cs); >>>> >>>> + if (config->mode & SPI_LOOP) >>>> + lpb |= MX51_ECSPI_LOOP; >>>> + >>>> writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL); >>>> writel(cfg, spi_imx->base + MX51_ECSPI_CONFIG); >>>> + writel(lpb, spi_imx->base + MX51_ECSPI_TEST); >>> It's better write this MX51_ECSPI_TEST only in LOOP mode. >> LOOP mode can be set dynamically. This mean we should be able to set and clear the flag. >> Currently only LOOP flag is used. I did not find any problems with writing 0 in the rest >> fields of TEST register. > Yes, I know writing 0 is harmless, but we never need to touch this register if > SPI_LOOP flags not set, I'd like below: > if (config->mode & SPI_LOOP) { > lpb |= MX51_ECSPI_LOOP; > writel(lgb, spi_imx->base + MX51_ECSPI_TEST); > } > Proposed code not able to clear LOOP mode in TEST register. What about something like this: if (config->mode & SPI_LOOP) lpb |= MX51_ECSPI_LOOP; if ((readl(spi_imx->base + MX51_ECSPI_TEST) & MX51_ECSPI_LOOP) != lpb) writel(lpb, spi_imx->base + MX51_ECSPI_TEST); In this case driver will write TEST register only if needed. >>>> >>>> /* >>>> * Wait until the changes in the configuration register CONFIGREG Regards, Anton