From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: [PATCH] mmc: core: Lower max_seg_size if too high for DMA Date: Wed, 31 Oct 2018 08:57:38 -0700 Message-ID: <20181031155738.18367-1-tony@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Ulf Hansson Cc: linux-mmc@vger.kernel.org, Kishon Vijay Abraham I , Peter Ujfalusi , Russell King , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: linux-omap@vger.kernel.org With CONFIG_DMA_API_DEBUG_SG a device may produce the following warning: "DMA-API: mapping sg segment longer than device claims to support" We default to 64KiB if a DMA engine driver does not initialize dma_parms and call dma_set_max_seg_size(). This may be lower that what many MMC drivers do with mmc->max_seg_size = mmc->max_blk_size * mmc->max_blk_count. Let's do a sanity check for max_seg_size being higher than what DMA supports in mmc_add_host() and lower it as needed. Cc: Kishon Vijay Abraham I Cc: Peter Ujfalusi Cc: Russell King Reported-by: Russell King Signed-off-by: Tony Lindgren --- drivers/mmc/core/host.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c --- a/drivers/mmc/core/host.c +++ b/drivers/mmc/core/host.c @@ -13,6 +13,7 @@ */ #include +#include #include #include #include @@ -415,6 +416,19 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev) EXPORT_SYMBOL(mmc_alloc_host); +static void mmc_check_max_seg_size(struct mmc_host *host) +{ + unsigned int max_seg_size = dma_get_max_seg_size(mmc_dev(host)); + + if (host->max_seg_size <= max_seg_size) + return; + + dev_info(mmc_dev(host), "Lowering max_seg_size for DMA: %u vs %u\n", + host->max_seg_size, max_seg_size); + + host->max_seg_size = max_seg_size; +} + /** * mmc_add_host - initialise host hardware * @host: mmc host @@ -430,6 +444,8 @@ int mmc_add_host(struct mmc_host *host) WARN_ON((host->caps & MMC_CAP_SDIO_IRQ) && !host->ops->enable_sdio_irq); + mmc_check_max_seg_size(host); + err = device_add(&host->class_dev); if (err) return err; -- 2.19.1