From: s.hauer@pengutronix.de (Sascha Hauer) Date: Wed, 5 Mar 2014 12:57:07 +0100 Subject: [PATCH 1/4] mfd: mc13xxx: Honor designed SPI mode In-Reply-To: <1393966265.723735713@f346.i.mail.ru> References: <1393746275-9253-1-git-send-email-shc_work@mail.ru> <1393840265.156525459@f373.i.mail.ru> <20140304201312.GR17250@pengutronix.de> <1393966265.723735713@f346.i.mail.ru> Message-ID: <20140305115707.GU17250@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Mar 05, 2014 at 12:51:05AM +0400, Alexander Shiyan wrote: > ???????, 4 ????? 2014, 21:13 +01:00 ?? Sascha Hauer : > > On Mon, Mar 03, 2014 at 01:51:05PM +0400, Alexander Shiyan wrote: > > > ???????????, 3 ????? 2014, 10:41 +01:00 ?? Sascha Hauer : > > > > On Sun, Mar 02, 2014 at 11:44:32AM +0400, Alexander Shiyan wrote: > > > > > Instead of using hard coded SPI mode, use mode described in > > > > > devicetree or defined for the board. > > > > > Additionally, patch updates all users of this PMIC to use > > > > > correct SPI mode. > > > > > > > > What's the reason for this change? Without it the driver just does the > > > > correct thing, this only adds a chance for boards do get it wrong. This > > > > for example happens with the i.MX27 phyCORE in this patch, see > > > > happens with arch/arm/boot/dts/imx27-phytec-phycore-som.dts whih doesn't > > > > have the spi-cs-high property. > > > > > > How specify proper functionality if chipselect connected through inverter? > > > > Is there such a hardware around? > > AFAIK no, but it is a protection for the future. Since this driver handle several PMICs, > we must anticipate the addition of new types of ICs and the emergence of new > devices using these PMICs, which could use external logic for chipselect. > Instead use tricks, use proper definitions (or DT description), from my point of view, > better. In that case rather than breaking devicetree compatibility we really should leave this problem to someone who actually has this problem. He could introduce an explicit spi-cs-low property to overwrite the driver preference. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |