From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D238D15C82 for ; Mon, 5 Dec 2022 19:19:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 570CAC433D6; Mon, 5 Dec 2022 19:19:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1670267945; bh=w9KGRntzBkhBwrHXOH/VZK9iq0Ck1XmrFUPD30d801w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=v7IjvuuZNSNosltpSpnYmdxnk5MuTuKUEMu696+u0cQcXgm466WUVqb4oCUwSjOEP 2boJWYQqMwAEBY83o4vyNoJItvh5hIB+WweN2IJNh1sK5b75RL1jhzgnYakvRt9+di Rg/MTkFcvZKzQBqMKN6ZBp8GfymRNwvdGYwmvM+Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sean Nyekjaer , Mark Brown , Sasha Levin Subject: [PATCH 4.19 004/105] spi: stm32: fix stm32_spi_prepare_mbr() that halves spi clk for every run Date: Mon, 5 Dec 2022 20:08:36 +0100 Message-Id: <20221205190803.271461958@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221205190803.124472741@linuxfoundation.org> References: <20221205190803.124472741@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Sean Nyekjaer [ Upstream commit 62aa1a344b0904549f6de7af958e8a1136fd5228 ] When this driver is used with a driver that uses preallocated spi_transfer structs. The speed_hz is halved by every run. This results in: spi_stm32 44004000.spi: SPI transfer setup failed ads7846 spi0.0: SPI transfer failed: -22 Example when running with DIV_ROUND_UP(): - First run; speed_hz = 1000000, spi->clk_rate 125000000 div 125 -> mbrdiv = 7, cur_speed = 976562 - Second run; speed_hz = 976562 div 128,00007 (roundup to 129) -> mbrdiv = 8, cur_speed = 488281 - Third run; speed_hz = 488281 div 256,000131072067109 (roundup to 257) and then -EINVAL is returned. Use DIV_ROUND_CLOSEST to allow to round down and allow us to keep the set speed. Signed-off-by: Sean Nyekjaer Link: https://lore.kernel.org/r/20221103080043.3033414-1-sean@geanix.com Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- drivers/spi/spi-stm32.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c index 8d692f16d90a..b8565da54a72 100644 --- a/drivers/spi/spi-stm32.c +++ b/drivers/spi/spi-stm32.c @@ -255,7 +255,7 @@ static int stm32_spi_prepare_mbr(struct stm32_spi *spi, u32 speed_hz) u32 div, mbrdiv; /* Ensure spi->clk_rate is even */ - div = DIV_ROUND_UP(spi->clk_rate & ~0x1, speed_hz); + div = DIV_ROUND_CLOSEST(spi->clk_rate & ~0x1, speed_hz); /* * SPI framework set xfer->speed_hz to master->max_speed_hz if -- 2.35.1