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([2a01:e0a:982:cbb0:b771:c77b:f889:9833]) by smtp.gmail.com with ESMTPSA id p14-20020adfce0e000000b0022af6c93340sm1199236wrn.17.2022.09.27.01.30.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 27 Sep 2022 01:30:06 -0700 (PDT) Message-ID: <09081275-be9c-9d0c-856b-ed2df8fc0b13@linaro.org> Date: Tue, 27 Sep 2022 10:30:06 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Reply-To: neil.armstrong@linaro.org Subject: Re: [PATCH 0/2] spi: amlogic: meson-spicc: Use pinctrl to drive CLK line when idle Content-Language: en-US To: Amjad Ouled-Ameur , broonie@kernel.org Cc: linux-kernel@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-spi@vger.kernel.org, narmstrong@baylibre.com References: <20220809172017.215412-1-aouledameur@baylibre.com> From: Neil Armstrong Organization: Linaro Developer Services In-Reply-To: <20220809172017.215412-1-aouledameur@baylibre.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Amjad, On 09/08/2022 19:20, Amjad Ouled-Ameur wrote: > Between SPI transactions, all SPI pins are in HiZ state. When using the SS > signal from the SPICC controller it's not an issue because when the > transaction resumes all pins come back to the right state at the same time > as SS. > > The problem is when we use CS as a GPIO. In fact, between the GPIO CS > state change and SPI pins state change from idle, you can have a missing or > spurious clock transition. > > Set a bias on the clock depending on the clock polarity requested before CS > goes active, by passing a special "idle-low" and "idle-high" pinctrl state > and setting the right state at a start of a message. > > Amjad Ouled-Ameur (2): > spi: dt-bindings: amlogic, meson-gx-spicc: Add pinctrl names for SPI > signal states > spi: meson-spicc: Use pinctrl to drive CLK line when idle > > .../bindings/spi/amlogic,meson-gx-spicc.yaml | 15 +++++++ > arch/arm64/boot/dts/amlogic/meson-gxl.dtsi | 14 +++++++ > drivers/spi/spi-meson-spicc.c | 39 ++++++++++++++++++- > 3 files changed, 67 insertions(+), 1 deletion(-) > Will you send a v2 with comments adresses ?