linux-kernel - [PATCH 1/4] mmc: mmci_sdmmc: fix DMA API warning max segment size

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Message-ID: <20200226084014.5242-2-ludovic.barre@st.com>
Date:   Wed, 26 Feb 2020 09:40:11 +0100
From:   Ludovic Barre <ludovic.barre@...com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>
CC:     <srinivas.kandagatla@...aro.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-mmc@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        Ludovic Barre <ludovic.barre@...com>
Subject: [PATCH 1/4] mmc: mmci_sdmmc: fix DMA API warning max segment size

Turning on CONFIG_DMA_API_DEBUG_SG results in the following warning:
WARNING: CPU: 1 PID: 85 at kernel/dma/debug.c:1302 debug_dma_map_sg+0x2a0/0x3cc
mmci-pl18x 58005000.sdmmc: DMA-API: mapping sg segment longer than device claims to support [len=126976] [max=65536]

dma api debug checks and compares the segment size to
dma_get_max_seg_size (dev->dma_parms->max_segment_size),
the sdmmc variant has an internal DMA and should define
its max_segment_size constraint to avoid this warning.

This Patch defines the dev->dma_parms->max_segment_size
with the constraint already set for mmc core
(host->mmc->max_seg_size).

Signed-off-by: Ludovic Barre <ludovic.barre@...com>
---
 drivers/mmc/host/mmci_stm32_sdmmc.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
index f76e82f8f12f..56d9ad7f523e 100644
--- a/drivers/mmc/host/mmci_stm32_sdmmc.c
+++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
@@ -119,20 +119,20 @@ static void sdmmc_idma_unprep_data(struct mmci_host *host,
 static int sdmmc_idma_setup(struct mmci_host *host)
 {
 	struct sdmmc_idma *idma;
+	struct device *dev = mmc_dev(host->mmc);
 
-	idma = devm_kzalloc(mmc_dev(host->mmc), sizeof(*idma), GFP_KERNEL);
-	if (!idma)
+	idma = devm_kzalloc(dev, sizeof(*idma), GFP_KERNEL);
+	dev->dma_parms = devm_kzalloc(dev, sizeof(*dev->dma_parms), GFP_KERNEL);
+	if (!idma || !dev->dma_parms)
 		return -ENOMEM;
 
 	host->dma_priv = idma;
 
 	if (host->variant->dma_lli) {
-		idma->sg_cpu = dmam_alloc_coherent(mmc_dev(host->mmc),
-						   SDMMC_LLI_BUF_LEN,
+		idma->sg_cpu = dmam_alloc_coherent(dev, SDMMC_LLI_BUF_LEN,
 						   &idma->sg_dma, GFP_KERNEL);
 		if (!idma->sg_cpu) {
-			dev_err(mmc_dev(host->mmc),
-				"Failed to alloc IDMA descriptor\n");
+			dev_err(dev, "Failed to alloc IDMA descriptor\n");
 			return -ENOMEM;
 		}
 		host->mmc->max_segs = SDMMC_LLI_BUF_LEN /
@@ -143,6 +143,8 @@ static int sdmmc_idma_setup(struct mmci_host *host)
 		host->mmc->max_seg_size = host->mmc->max_req_size;
 	}
 
+	dma_set_max_seg_size(dev, host->mmc->max_seg_size);
+
 	return 0;
 }
 
-- 
2.17.1