mmc: renesas_sdhi_internal_dmac: set scatter/gather max segment size

Niklas Söderlund · storulf · commit 54541815b43f · 2018-10-08T11:40:43.000+02:00
Fix warning when running with CONFIG_DMA_API_DEBUG_SG=y by allocating a
device_dma_parameters structure and filling in the max segment size. The
size used is the result of a discussion with Renesas hardware engineers
and unfortunately not found in the datasheet.

  renesas_sdhi_internal_dmac ee140000.sd: DMA-API: mapping sg segment
  longer than device claims to support [len=126976] [max=65536]

Reported-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
Signed-off-by: Niklas Söderlund &lt;niklas.soderlund+renesas@ragnatech.se&gt;
[wsa: simplified some logic after validating intended dma_parms life cycle
      and added comment]
Signed-off-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
Signed-off-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt;
diff --git a/drivers/mmc/host/renesas_sdhi_internal_dmac.c b/drivers/mmc/host/renesas_sdhi_internal_dmac.c
@@ -308,12 +308,20 @@ static const struct soc_device_attribute gen3_soc_whitelist[] = {
 static int renesas_sdhi_internal_dmac_probe(struct platform_device *pdev)
 {
 	const struct soc_device_attribute *soc = soc_device_match(gen3_soc_whitelist);
+	struct device *dev = &pdev->dev;
 
 	if (!soc)
 		return -ENODEV;
 
 	global_flags |= (unsigned long)soc->data;
 
+	dev->dma_parms = devm_kzalloc(dev, sizeof(*dev->dma_parms), GFP_KERNEL);
+	if (!dev->dma_parms)
+		return -ENOMEM;
+
+	/* value is max of SD_SECCNT. Confirmed by HW engineers */
+	dma_set_max_seg_size(dev, 0xffffffff);
+
 	return renesas_sdhi_probe(pdev, &renesas_sdhi_internal_dmac_dma_ops);
 }
 
