From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH v2] DTS: ARM: gta04: introduce legacy spi-cs-high to make display work again Date: Mon, 23 Sep 2019 10:34:41 -0700 Message-ID: <20190923173441.GV5610@atomide.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: =?utf-8?Q?Beno=C3=AEt?= Cousson , Rob Herring , Mark Rutland , broonie@kernel.org, linus.walleij@linaro.org, stable@vger.kernel.org, linux-spi@vger.kernel.org, linux-omap@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, letux-kernel@openphoenux.org, kernel@pyra-handheld.com To: "H. Nikolaus Schaller" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-spi.vger.kernel.org * H. Nikolaus Schaller [190920 09:12]: > commit 6953c57ab172 "gpio: of: Handle SPI chipselect legacy bindings" > > did introduce logic to centrally handle the legacy spi-cs-high property > in combination with cs-gpios. This assumes that the polarity > of the CS has to be inverted if spi-cs-high is missing, even > and especially if non-legacy GPIO_ACTIVE_HIGH is specified. > > The DTS for the GTA04 was orginally introduced under the assumption > that there is no need for spi-cs-high if the gpio is defined with > proper polarity GPIO_ACTIVE_HIGH. > > This was not a problem until gpiolib changed the interpretation of > GPIO_ACTIVE_HIGH and missing spi-cs-high. > > The effect is that the missing spi-cs-high is now interpreted as CS being > low (despite GPIO_ACTIVE_HIGH) which turns off the SPI interface when the > panel is to be programmed by the panel driver. > > Therefore, we have to add the redundant and legacy spi-cs-high property > to properly activate CS. Thanks applying into fixes. Tony