Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <d1039404-b8db-c32c-d508-32a77a348744@baylibre.com>
Date:   Tue, 27 Sep 2022 11:36:49 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.3.0
Subject: Re: [PATCH 0/2] spi: amlogic: meson-spicc: Use pinctrl to drive CLK
 line when idle
Content-Language: en-US
To:     neil.armstrong@linaro.org, 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>
 <09081275-be9c-9d0c-856b-ed2df8fc0b13@linaro.org>
From:   Amjad Ouled-Ameur <aouledameur@baylibre.com>
In-Reply-To: <09081275-be9c-9d0c-856b-ed2df8fc0b13@linaro.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

Hi Neil,

On 9/27/22 10:30, Neil Armstrong wrote:
> 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 ?

Planning to send it soon, thank you for the review.

Regards,

Amjad