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 64F767DA78; Thu, 15 Aug 2024 13:36:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723728977; cv=none; b=MlYVpH+5/LxBpwCMhZPCuSfVq+sm96D7vzpQq4mBo2VZGDgTnIouUTd9W4tUsN4q5HNRq3DR4i0iUhS1vPWa+wIyZ73Gr2k/FSHHh0RNnY27auSDnEbWXN/WoBR5tRmFianzzS943C6YecWjnWdFpFgSTZFN/2C6bx5qPIGF/LI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723728977; c=relaxed/simple; bh=1hRREk6sC5zGfmOFWpNj6dKZwZZ34Ls6VabanM7VH5o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MjHqzEz7p9zJsxxIrYU6B5aiXbtFOfVNhY+8cyBuzgtUcNcsQ95ajdWLsTMA4/3EPHe20Hpc+om8VGmF2rqg9YTDLTEuKyDgHlKpqdKIe7KJkJrmLqkzsedNzkHnK9VFdERfokDXrMtxqm/rLLTQ9ydPoYM3ioS6pewlBvmxWkw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=NKGwy9J0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="NKGwy9J0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DDE95C32786; Thu, 15 Aug 2024 13:36:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723728977; bh=1hRREk6sC5zGfmOFWpNj6dKZwZZ34Ls6VabanM7VH5o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NKGwy9J0xDfAuta2nBcZ4vjyhxxCqSSxvNwh+qpKVHjZLkTJ5N4Q1RuP7pR3rGUGz iGcOiq5+pVYBnnDZ1huIFtc8V8rME7K2U1teIfwsgphZaSEi1ymRNyijNdUNgA2TNi rTVNnDGc70F+uvwkd4LjbRItx7XTxMkjjMJ5MJL4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Stefan Wahren , Mark Brown , Sasha Levin Subject: [PATCH 4.19 171/196] spi: spi-fsl-lpspi: Fix scldiv calculation Date: Thu, 15 Aug 2024 15:24:48 +0200 Message-ID: <20240815131858.613083596@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240815131852.063866671@linuxfoundation.org> References: <20240815131852.063866671@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stefan Wahren [ Upstream commit 730bbfaf7d4890bd99e637db7767dc68cfeb24e7 ] The effective SPI clock frequency should never exceed speed_hz otherwise this might result in undefined behavior of the SPI device. Currently the scldiv calculation could violate this constraint. For the example parameters perclk_rate = 24 MHz and speed_hz = 7 MHz, the function fsl_lpspi_set_bitrate will determine perscale = 0 and scldiv = 1, which is a effective SPI clock of 8 MHz. So fix this by rounding up the quotient of perclk_rate and speed_hz. While this never change within the loop, we can pull this out. Fixes: 5314987de5e5 ("spi: imx: add lpspi bus driver") Signed-off-by: Stefan Wahren Link: https://patch.msgid.link/20240804113611.83613-1-wahrenst@gmx.net Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- drivers/spi/spi-fsl-lpspi.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/spi/spi-fsl-lpspi.c +++ b/drivers/spi/spi-fsl-lpspi.c @@ -257,7 +257,7 @@ static void fsl_lpspi_set_watermark(stru static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi) { struct lpspi_config config = fsl_lpspi->config; - unsigned int perclk_rate, scldiv; + unsigned int perclk_rate, scldiv, div; u8 prescale; perclk_rate = clk_get_rate(fsl_lpspi->clk_per); @@ -268,8 +268,10 @@ static int fsl_lpspi_set_bitrate(struct return -EINVAL; } + div = DIV_ROUND_UP(perclk_rate, config.speed_hz); + for (prescale = 0; prescale < 8; prescale++) { - scldiv = perclk_rate / config.speed_hz / (1 << prescale) - 2; + scldiv = div / (1 << prescale) - 2; if (scldiv < 256) { fsl_lpspi->config.prescale = prescale; break;