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b=CmKkWRuW1/JZR8nVF/hgui5hysfrE1M30OsnUqPmbD6tT/OftNCKq6DK2XkU4SUy Txw87D4X2NWA7C3zMMytymZsp/ywTENNAGw3BKBrfZVfiENl2jHbmkBQE69IxlXo4 A+nRWbe+j0KbHWIED0heYrkP7rXbuP4U5OVg15B/olofx70sNdIKgSCJiAgN4UKrs 6+KaolXjbj4OrYHMTuE8zN1Z+Iu5HwfNDuP9EEKEYCjUhFnUgdG7DJoXlkRPesD+4 r4seu9CGpzCyfRryOu3JxtOLdyA66WmlcVJjQQZ6wcCK408XoflRZ8PKB46U29X6U rBiBvT08id/GpltYRw== X-UI-Sender-Class: 55c96926-9e95-11ee-ae09-1f7a4046a0f6 Received: from client.hidden.invalid by mrelayeu.kundenserver.de (mreue107 [213.165.67.113]) with ESMTPSA (Nemesis) id 1N8GAQ-1wlp0h3dMO-00tSJl; Sat, 19 Sep 2026 19:02:07 +0200 Message-ID: <027f8dea-2661-4ece-b4f0-d772e81cc6e5@jonasjelonek.de> Date: Sat, 19 Sep 2026 19:02:07 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] spi: realtek-rtl: add support for second CS Content-Language: en-US To: Mark Brown Cc: linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260918214740.3963349-1-jonas@jonasjelonek.de> From: Jonas Jelonek In-Reply-To: Content-Type: text/plain; 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This >> does not hold for all hardware: there are devices with a peripheral >> connected to CS1. Since the controller only advertises one chip select >> and keeps CS1 permanently deasserted, those peripherals cannot be used. >> + /* CSB0/CSB1 are active low: deassert both. */ >> value = __raw_readl(REG(RTL_SPI_SFCSR)); >> - /* Permanently disable CS1, since it's never used */ >> - value |= RTL_SPI_SFCSR_CSB1; >> - /* Select CS0 for use */ >> - value &= RTL_SPI_SFCSR_CS; >> + value |= RTL_SPI_SFCSR_CSB0 | RTL_SPI_SFCSR_CSB1; >> __raw_writel(value, REG(RTL_SPI_SFCSR)); > The original code would ensure that all bits in the register are > initialised to known values, the new code sets some bits and leaves the > rest with whatever value they happened to have previously. Probably we > still want the initialisation of the other bits. Yes, you're right. Thanks for pointing that out. Indeed, bits setting the data length and the I/O mode sit in this register too. Zero is required to have one byte data length and single I/O. I'll fix this in a v2. Best, Jonas