From: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
To: Adrian Hunter <adrian.hunter@intel.com>,
Ulf Hansson <ulf.hansson@linaro.org>
Cc: <linux-mmc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>
Subject: [PATCH v5 3/3] mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation
Date: Mon, 27 Aug 2018 16:24:19 +0800 [thread overview]
Message-ID: <20180827162419.61afe238@xhacker.debian> (raw)
In-Reply-To: <20180827162026.3901de27@xhacker.debian>
When using DMA, if the DMA addr spans 128MB boundary, we have to split
the DMA transfer into two so that each one doesn't exceed the boundary.
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
---
drivers/mmc/host/sdhci-of-dwcmshc.c | 41 +++++++++++++++++++++++++++++
1 file changed, 41 insertions(+)
diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
index 1b7cd144fb01..cfbdae8703a1 100644
--- a/drivers/mmc/host/sdhci-of-dwcmshc.c
+++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
@@ -8,21 +8,50 @@
*/
#include <linux/clk.h>
+#include <linux/mm.h>
#include <linux/module.h>
#include <linux/of.h>
+#include <linux/sizes.h>
#include "sdhci-pltfm.h"
+#define BOUNDARY_OK(addr, len) \
+ ((addr | (SZ_128M - 1)) == ((addr + len - 1) | (SZ_128M - 1)))
+
struct dwcmshc_priv {
struct clk *bus_clk;
};
+/*
+ * If DMA addr spans 128MB boundary, we split the DMA transfer into two
+ * so that each DMA transfer doesn't exceed the boundary.
+ */
+static void dwcmshc_adma_write_desc(struct sdhci_host *host, void **desc,
+ dma_addr_t addr, int len, unsigned int cmd)
+{
+ int tmplen, offset;
+
+ if (likely(!len || BOUNDARY_OK(addr, len))) {
+ sdhci_adma_write_desc(host, desc, addr, len, cmd);
+ return;
+ }
+
+ offset = addr & (SZ_128M - 1);
+ tmplen = SZ_128M - offset;
+ sdhci_adma_write_desc(host, desc, addr, tmplen, cmd);
+
+ addr += tmplen;
+ len -= tmplen;
+ sdhci_adma_write_desc(host, desc, addr, len, cmd);
+}
+
static const struct sdhci_ops sdhci_dwcmshc_ops = {
.set_clock = sdhci_set_clock,
.set_bus_width = sdhci_set_bus_width,
.set_uhs_signaling = sdhci_set_uhs_signaling,
.get_max_clock = sdhci_pltfm_clk_get_max_clock,
.reset = sdhci_reset,
+ .adma_write_desc = dwcmshc_adma_write_desc,
};
static const struct sdhci_pltfm_data sdhci_dwcmshc_pdata = {
@@ -36,12 +65,24 @@ static int dwcmshc_probe(struct platform_device *pdev)
struct sdhci_host *host;
struct dwcmshc_priv *priv;
int err;
+ u32 extra;
host = sdhci_pltfm_init(pdev, &sdhci_dwcmshc_pdata,
sizeof(struct dwcmshc_priv));
if (IS_ERR(host))
return PTR_ERR(host);
+ /*
+ * The DMA table descriptor count is calculated as the maximum
+ * number of segments times 2, to allow for an alignment
+ * descriptor for each segment, plus 1 for a nop end descriptor,
+ * plus extra number for cross 128M boundary handling.
+ */
+ extra = DIV_ROUND_UP(totalram_pages, SZ_128M / PAGE_SIZE);
+ if (extra > SDHCI_MAX_SEGS)
+ extra = SDHCI_MAX_SEGS;
+ host->adma_table_cnt += extra;
+
pltfm_host = sdhci_priv(host);
priv = sdhci_pltfm_priv(pltfm_host);
--
2.18.0
next prev parent reply other threads:[~2018-08-27 8:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-27 8:20 [PATCH v5 0/3] solve SDHCI DWC MSHC 128MB DMA boundary limitation Jisheng Zhang
2018-08-27 8:21 ` [PATCH v5 1/3] mmc: sdhci: add adma_table_cnt member to struct sdhci_host Jisheng Zhang
2018-08-27 8:22 ` [PATCH v5 2/3] mmc: sdhci: introduce adma_write_desc() hook to struct sdhci_ops Jisheng Zhang
2018-08-27 8:24 ` Jisheng Zhang [this message]
2018-08-28 7:51 ` [PATCH v5 3/3] mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation Adrian Hunter
2018-08-28 9:53 ` Jisheng Zhang
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