Re: [PATCH v4 3/3] mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation
On Thu, 23 Aug 2018 14:51:26 +0300 Adrian Hunter wrote:
> On 23/08/18 13:09, Jisheng Zhang wrote:
> > 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
> > ---
> > drivers/mmc/host/sdhci-of-dwcmshc.c | 39 +
> > 1 file changed, 39 insertions(+)
> >
> > diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c
> > b/drivers/mmc/host/sdhci-of-dwcmshc.c
> > index 1b7cd144fb01..df0a3aeabe19 100644
> > --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> > +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> > @@ -8,21 +8,48 @@
> > */
> >
> > #include
> > +#include
> > #include
> > #include
> > +#include
> >
> > #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 the 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);
>
> Doesn't this need a return? i.e.
>
> return;
oops, I made a mistake here. Pre v4, there's a return...
Thanks so much.
> }
>
> > +
> > + 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 +63,24 @@ 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);
>
> You are assuming here that totalram_pages gives you the highest physical
> page number. Is that true?
Per my understanding, it's true. What I need is the MemTotal/PAGE_SIZE where
Memtotal is from /proc/meminfo. After reading the code, I found this is
totalram_pages as shown in si_meminfo()
>
> > + if (extra > SDHCI_MAX_SEGS)
> > + extra = SDHCI_MAX_SEGS;
> > + host->adma_table_cnt = SDHCI_MAX_SEGS * 2 + 1 + extra;
>
> That should be:
>
> host->adma_table_cnt += extra;
yep, will do in v5
>
> > +
> > pltfm_host = sdhci_priv(host);
> > priv = sdhci_pltfm_priv(pltfm_host);
> >
> >
>
Re: [PATCH v4 3/3] mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation
On 23/08/18 13:09, Jisheng Zhang wrote:
> 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
> ---
> drivers/mmc/host/sdhci-of-dwcmshc.c | 39 +
> 1 file changed, 39 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c
> b/drivers/mmc/host/sdhci-of-dwcmshc.c
> index 1b7cd144fb01..df0a3aeabe19 100644
> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> @@ -8,21 +8,48 @@
> */
>
> #include
> +#include
> #include
> #include
> +#include
>
> #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 the 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);
Doesn't this need a return? i.e.
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 +63,24 @@ 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);
You are assuming here that totalram_pages gives you the highest physical
page number. Is that true?
> + if (extra > SDHCI_MAX_SEGS)
> + extra = SDHCI_MAX_SEGS;
> + host->adma_table_cnt = SDHCI_MAX_SEGS * 2 + 1 + extra;
That should be:
host->adma_table_cnt += extra;
> +
> pltfm_host = sdhci_priv(host);
> priv = sdhci_pltfm_priv(pltfm_host);
>
>
[PATCH v4 3/3] mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation
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
---
drivers/mmc/host/sdhci-of-dwcmshc.c | 39 +
1 file changed, 39 insertions(+)
diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c
b/drivers/mmc/host/sdhci-of-dwcmshc.c
index 1b7cd144fb01..df0a3aeabe19 100644
--- a/drivers/mmc/host/sdhci-of-dwcmshc.c
+++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
@@ -8,21 +8,48 @@
*/
#include
+#include
#include
#include
+#include
#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 the 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);
+
+ 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 +63,24 @@ 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 = SDHCI_MAX_SEGS * 2 + 1 + extra;
+
pltfm_host = sdhci_priv(host);
priv = sdhci_pltfm_priv(pltfm_host);
--
2.18.0
