Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753074AbbDFV3N (ORCPT ); Mon, 6 Apr 2015 17:29:13 -0400 Received: from mail-qk0-f201.google.com ([209.85.220.201]:34141 "EHLO mail-qk0-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752683AbbDFV3J (ORCPT ); Mon, 6 Apr 2015 17:29:09 -0400 From: Andrew Bresticker To: Mark Brown Cc: linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Bresticker Subject: [PATCH 1/5] spi: img-spfi: Limit bit clock to 1/4th of input clock Date: Mon, 6 Apr 2015 14:29:03 -0700 Message-Id: <1428355747-16822-1-git-send-email-abrestic@chromium.org> X-Mailer: git-send-email 2.2.0.rc0.207.ga3a616c Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1937 Lines: 46 Although the SPFI BITCLK divider supports a value of up to 255, only values up to 128 are usable. This results in a maximum possible bit clock rate of 1/4th the input clock rate. Signed-off-by: Andrew Bresticker --- drivers/spi/spi-img-spfi.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/spi/spi-img-spfi.c b/drivers/spi/spi-img-spfi.c index e649bc7..7d18bec 100644 --- a/drivers/spi/spi-img-spfi.c +++ b/drivers/spi/spi-img-spfi.c @@ -405,10 +405,10 @@ static void img_spfi_config(struct spi_master *master, struct spi_device *spi, /* * output = spfi_clk * (BITCLK / 512), where BITCLK must be a - * power of 2 up to 256 (where 255 == 256 since BITCLK is 8 bits) + * power of 2 up to 128 */ - div = DIV_ROUND_UP(master->max_speed_hz, xfer->speed_hz); - div = clamp(512 / (1 << get_count_order(div)), 1, 255); + div = DIV_ROUND_UP(clk_get_rate(spfi->spfi_clk), xfer->speed_hz); + div = clamp(512 / (1 << get_count_order(div)), 1, 128); val = spfi_readl(spfi, SPFI_DEVICE_PARAMETER(spi->chip_select)); val &= ~(SPFI_DEVICE_PARAMETER_BITCLK_MASK << @@ -594,8 +594,8 @@ static int img_spfi_probe(struct platform_device *pdev) master->num_chipselect = 5; master->dev.of_node = pdev->dev.of_node; master->bits_per_word_mask = SPI_BPW_MASK(32) | SPI_BPW_MASK(8); - master->max_speed_hz = clk_get_rate(spfi->spfi_clk); - master->min_speed_hz = master->max_speed_hz / 512; + master->max_speed_hz = clk_get_rate(spfi->spfi_clk) / 4; + master->min_speed_hz = clk_get_rate(spfi->spfi_clk) / 512; master->set_cs = img_spfi_set_cs; master->transfer_one = img_spfi_transfer_one; -- 2.2.0.rc0.207.ga3a616c -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/