Re: [PATCH v4 2/4] mmc: dw_mmc-rockchip: Add internal phase support

Hello Detlev,

On 2024-08-23 15:34, Detlev Casanova wrote:

On Friday, 23 August 2024 01:41:44 EDT Dragan Simic wrote:

quoted

Hello Detlev,

Please see a comment below.

On 2024-08-22 23:15, Detlev Casanova wrote:

quoted

From: Shawn Lin <shawn.lin@rock-chips.com>

Some Rockchip devices put the phase settings into the dw_mmc
controller.

When the feature is present, the ciu-drive and ciu-sample clocks are
not used and the phase configuration is done directly through the mmc
controller.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
---

 drivers/mmc/host/dw_mmc-rockchip.c | 171 +++++++++++++++++++++++++++--
 1 file changed, 160 insertions(+), 11 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc-rockchip.c

b/drivers/mmc/host/dw_mmc-rockchip.c
index b07190ba4b7a..2748f9bf2691 100644

--- a/drivers/mmc/host/dw_mmc-rockchip.c
+++ b/drivers/mmc/host/dw_mmc-rockchip.c

@@ -15,7 +15,17 @@

 #include "dw_mmc.h"
 #include "dw_mmc-pltfm.h"

-#define RK3288_CLKGEN_DIV	2
+#define RK3288_CLKGEN_DIV		2
+#define SDMMC_TIMING_CON0		0x130
+#define SDMMC_TIMING_CON1		0x134
+#define ROCKCHIP_MMC_DELAY_SEL		BIT(10)
+#define ROCKCHIP_MMC_DEGREE_MASK	0x3
+#define ROCKCHIP_MMC_DEGREE_OFFSET	1
+#define ROCKCHIP_MMC_DELAYNUM_OFFSET	2
+#define ROCKCHIP_MMC_DELAYNUM_MASK	(0xff <<

ROCKCHIP_MMC_DELAYNUM_OFFSET)
+#define ROCKCHIP_MMC_DELAY_ELEMENT_PSEC	60
+#define HIWORD_UPDATE(val, mask, shift) \
+		((val) << (shift) | (mask) << ((shift) + 16))

 static const unsigned int freqs[] = { 100000, 200000, 300000, 400000

};

@@ -24,8 +34,143 @@ struct dw_mci_rockchip_priv_data {

 	struct clk		*sample_clk;
 	int			default_sample_phase;
 	int			num_phases;

+	int			internal_phase;

 };

It might be good to declare internal_phase as "unsigned int
internal_phase:1",
i.e. as a bit field, which isn't going to save some memory in this
particular
case, but it would show additional attention to detail.

In that case, I would go with a bool instead of int, that makes things
even clearer.

My suggestion to use "unsigned int internal_phase:1" actually takes
inspiration from the ASoC code, in which such bit fields are used
quite a lot, even when using them actually doesn't save space.

In this particular case, using plain bool would make sense, but I
still think that using an "unsigned int internal_phase:1" bit field
would fit better, because it would show the intention to possibly
save a bit of RAM at some point.  OTOH, I don't think that using
bool with such bit fields would actually work cleanly, because bool
actually resolves to int that's a signed type.