diff mbox

[2/5] drivers: mmc: sunxi: limit A64 MMC2 to 8K DMA buffer

Message ID 1483398226-29321-3-git-send-email-andre.przywara@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Andre Przywara Jan. 2, 2017, 11:03 p.m. UTC
From: Maxime Ripard <maxime.ripard@free-electrons.com>

Unlike the A64 user manual reports, the third MMC controller on the
A64 (and the only one capable of 8-bit HS400 eMMC transfers) has a
DMA buffer size limit of 8KB (much like the very old Allwinner SoCs).
This does not affect the other two controllers, so introduce a new
DT compatible string to let the driver use different settings for that
particular device. This will also help to enable the high-speed transfer
modes of that controller later.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 Documentation/devicetree/bindings/mmc/sunxi-mmc.txt | 1 +
 drivers/mmc/host/sunxi-mmc.c                        | 7 +++++++
 2 files changed, 8 insertions(+)

Comments

Rob Herring (Arm) Jan. 4, 2017, 2:07 p.m. UTC | #1
On Mon, Jan 02, 2017 at 11:03:43PM +0000, Andre Przywara wrote:
> From: Maxime Ripard <maxime.ripard@free-electrons.com>
> 
> Unlike the A64 user manual reports, the third MMC controller on the
> A64 (and the only one capable of 8-bit HS400 eMMC transfers) has a
> DMA buffer size limit of 8KB (much like the very old Allwinner SoCs).
> This does not affect the other two controllers, so introduce a new
> DT compatible string to let the driver use different settings for that
> particular device. This will also help to enable the high-speed transfer
> modes of that controller later.
> 
> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  Documentation/devicetree/bindings/mmc/sunxi-mmc.txt | 1 +
>  drivers/mmc/host/sunxi-mmc.c                        | 7 +++++++
>  2 files changed, 8 insertions(+)

Acked-by: Rob Herring <robh@kernel.org>
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Maxime Ripard Jan. 5, 2017, 5:57 p.m. UTC | #2
Hi Rob,

On Wed, Jan 04, 2017 at 08:07:50AM -0600, Rob Herring wrote:
> On Mon, Jan 02, 2017 at 11:03:43PM +0000, Andre Przywara wrote:
> > From: Maxime Ripard <maxime.ripard@free-electrons.com>
> > 
> > Unlike the A64 user manual reports, the third MMC controller on the
> > A64 (and the only one capable of 8-bit HS400 eMMC transfers) has a
> > DMA buffer size limit of 8KB (much like the very old Allwinner SoCs).
> > This does not affect the other two controllers, so introduce a new
> > DT compatible string to let the driver use different settings for that
> > particular device. This will also help to enable the high-speed transfer
> > modes of that controller later.
> > 
> > Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> > Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> > ---
> >  Documentation/devicetree/bindings/mmc/sunxi-mmc.txt | 1 +
> >  drivers/mmc/host/sunxi-mmc.c                        | 7 +++++++
> >  2 files changed, 8 insertions(+)
> 
> Acked-by: Rob Herring <robh@kernel.org>

Some kind of a digression on this: we have three MMC controllers on
this SoC. Like this patch shows, the third one is clearly different,
and supports both more modes, a wider bus, and specific quirks. We
need a new compatible for this one, everything's perfect.

However, the other two are mostly the same, but seems to need
different tuning parameters to get more performances out of the
controller (but this is unclear yet). How do we usually deal with
that?

Thanks,
Maxime
Andre Przywara Jan. 5, 2017, 11:33 p.m. UTC | #3
On 05/01/17 17:57, Maxime Ripard wrote:
> Hi Rob,
> 
> On Wed, Jan 04, 2017 at 08:07:50AM -0600, Rob Herring wrote:
>> On Mon, Jan 02, 2017 at 11:03:43PM +0000, Andre Przywara wrote:
>>> From: Maxime Ripard <maxime.ripard@free-electrons.com>
>>>
>>> Unlike the A64 user manual reports, the third MMC controller on the
>>> A64 (and the only one capable of 8-bit HS400 eMMC transfers) has a
>>> DMA buffer size limit of 8KB (much like the very old Allwinner SoCs).
>>> This does not affect the other two controllers, so introduce a new
>>> DT compatible string to let the driver use different settings for that
>>> particular device. This will also help to enable the high-speed transfer
>>> modes of that controller later.
>>>
>>> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
>>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>>> ---
>>>  Documentation/devicetree/bindings/mmc/sunxi-mmc.txt | 1 +
>>>  drivers/mmc/host/sunxi-mmc.c                        | 7 +++++++
>>>  2 files changed, 8 insertions(+)
>>
>> Acked-by: Rob Herring <robh@kernel.org>
> 
> Some kind of a digression on this: we have three MMC controllers on
> this SoC. Like this patch shows, the third one is clearly different,
> and supports both more modes, a wider bus, and specific quirks. We
> need a new compatible for this one, everything's perfect.
> 
> However, the other two are mostly the same, but seems to need
> different tuning parameters to get more performances out of the
> controller (but this is unclear yet). How do we usually deal with
> that?

I guess you wanted to hear Rob's opinion ;-), but "get more performance"
sounds like we add one (or more) properties to tune those values.
If I get this right, it works with default values, but is sub-optimal?

Cheers,
Andre.

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Maxime Ripard Jan. 10, 2017, 2:06 p.m. UTC | #4
On Thu, Jan 05, 2017 at 11:33:28PM +0000, André Przywara wrote:
> On 05/01/17 17:57, Maxime Ripard wrote:
> > Hi Rob,
> > 
> > On Wed, Jan 04, 2017 at 08:07:50AM -0600, Rob Herring wrote:
> >> On Mon, Jan 02, 2017 at 11:03:43PM +0000, Andre Przywara wrote:
> >>> From: Maxime Ripard <maxime.ripard@free-electrons.com>
> >>>
> >>> Unlike the A64 user manual reports, the third MMC controller on the
> >>> A64 (and the only one capable of 8-bit HS400 eMMC transfers) has a
> >>> DMA buffer size limit of 8KB (much like the very old Allwinner SoCs).
> >>> This does not affect the other two controllers, so introduce a new
> >>> DT compatible string to let the driver use different settings for that
> >>> particular device. This will also help to enable the high-speed transfer
> >>> modes of that controller later.
> >>>
> >>> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> >>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> >>> ---
> >>>  Documentation/devicetree/bindings/mmc/sunxi-mmc.txt | 1 +
> >>>  drivers/mmc/host/sunxi-mmc.c                        | 7 +++++++
> >>>  2 files changed, 8 insertions(+)
> >>
> >> Acked-by: Rob Herring <robh@kernel.org>
> > 
> > Some kind of a digression on this: we have three MMC controllers on
> > this SoC. Like this patch shows, the third one is clearly different,
> > and supports both more modes, a wider bus, and specific quirks. We
> > need a new compatible for this one, everything's perfect.
> > 
> > However, the other two are mostly the same, but seems to need
> > different tuning parameters to get more performances out of the
> > controller (but this is unclear yet). How do we usually deal with
> > that?
> 
> I guess you wanted to hear Rob's opinion ;-), but "get more performance"
> sounds like we add one (or more) properties to tune those values.
> If I get this right, it works with default values, but is sub-optimal?

That would be my understanding too, at least, it works in a decent way
without fiddling with those parameters.

Maxime
diff mbox

Patch

diff --git a/Documentation/devicetree/bindings/mmc/sunxi-mmc.txt b/Documentation/devicetree/bindings/mmc/sunxi-mmc.txt
index 55cdd80..3d9170f 100644
--- a/Documentation/devicetree/bindings/mmc/sunxi-mmc.txt
+++ b/Documentation/devicetree/bindings/mmc/sunxi-mmc.txt
@@ -14,6 +14,7 @@  Required properties:
    * "allwinner,sun7i-a20-mmc"
    * "allwinner,sun9i-a80-mmc"
    * "allwinner,sun50i-a64-mmc"
+   * "allwinner,sun50i-a64-emmc"
  - reg : mmc controller base registers
  - clocks : a list with 4 phandle + clock specifier pairs
  - clock-names : must contain "ahb", "mmc", "output" and "sample"
diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
index 1e156e8..165486bc 100644
--- a/drivers/mmc/host/sunxi-mmc.c
+++ b/drivers/mmc/host/sunxi-mmc.c
@@ -1097,12 +1097,19 @@  static const struct sunxi_mmc_cfg sun50i_a64_cfg = {
 	.can_calibrate = true,
 };
 
+static const struct sunxi_mmc_cfg sun50i_a64_emmc_cfg = {
+	.idma_des_size_bits = 13,
+	.clk_delays = sun50i_mmc_clk_delays,
+	.can_calibrate = true,
+};
+
 static const struct of_device_id sunxi_mmc_of_match[] = {
 	{ .compatible = "allwinner,sun4i-a10-mmc", .data = &sun4i_a10_cfg },
 	{ .compatible = "allwinner,sun5i-a13-mmc", .data = &sun5i_a13_cfg },
 	{ .compatible = "allwinner,sun7i-a20-mmc", .data = &sun7i_a20_cfg },
 	{ .compatible = "allwinner,sun9i-a80-mmc", .data = &sun9i_a80_cfg },
 	{ .compatible = "allwinner,sun50i-a64-mmc", .data = &sun50i_a64_cfg },
+	{ .compatible = "allwinner,sun50i-a64-emmc", .data = &sun50i_a64_emmc_cfg },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, sunxi_mmc_of_match);