* [RFC PATCH] clk: renesas: rcar-gen3: remove stp_ck handling for SDHI
@ 2020-09-14 9:04 Wolfram Sang
2020-09-14 9:35 ` Geert Uytterhoeven
0 siblings, 1 reply; 3+ messages in thread
From: Wolfram Sang @ 2020-09-14 9:04 UTC (permalink / raw)
To: linux-clk; +Cc: linux-renesas-soc, Geert Uytterhoeven, Wolfram Sang
There is no case (and none forseen) where we would need to disable the
SDn clock. So, for simplicity, remove its handling.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
One paradigm is to stay minimal and remove unneeded things. Another one
is to not change working code unnecessarily. I favor the first one a bit
more, but would understand arguing with the second one.
Despite that, tested on a Renesas Salvator-XS (M3-N) with eMMC and two
kinds of SD cards. Checksumming large files works at expected speeds.
drivers/clk/renesas/rcar-gen3-cpg.c | 51 ++++++++++++++---------------
1 file changed, 25 insertions(+), 26 deletions(-)
diff --git a/drivers/clk/renesas/rcar-gen3-cpg.c b/drivers/clk/renesas/rcar-gen3-cpg.c
index 488f8b3980c5..a7debddf7d09 100644
--- a/drivers/clk/renesas/rcar-gen3-cpg.c
+++ b/drivers/clk/renesas/rcar-gen3-cpg.c
@@ -224,10 +224,9 @@ static struct clk * __init cpg_z_clk_register(const char *name,
#define CPG_SD_STP_MASK (CPG_SD_STP_HCK | CPG_SD_STP_CK)
#define CPG_SD_FC_MASK (0x7 << 2 | 0x3 << 0)
-#define CPG_SD_DIV_TABLE_DATA(stp_hck, stp_ck, sd_srcfc, sd_fc, sd_div) \
+#define CPG_SD_DIV_TABLE_DATA(stp_hck, sd_srcfc, sd_fc, sd_div) \
{ \
.val = ((stp_hck) ? CPG_SD_STP_HCK : 0) | \
- ((stp_ck) ? CPG_SD_STP_CK : 0) | \
((sd_srcfc) << 2) | \
((sd_fc) << 0), \
.div = (sd_div), \
@@ -247,36 +246,36 @@ struct sd_clock {
};
/* SDn divider
- * sd_srcfc sd_fc div
- * stp_hck stp_ck (div) (div) = sd_srcfc x sd_fc
- *-------------------------------------------------------------------
- * 0 0 0 (1) 1 (4) 4 : SDR104 / HS200 / HS400 (8 TAP)
- * 0 0 1 (2) 1 (4) 8 : SDR50
- * 1 0 2 (4) 1 (4) 16 : HS / SDR25
- * 1 0 3 (8) 1 (4) 32 : NS / SDR12
- * 1 0 4 (16) 1 (4) 64
- * 0 0 0 (1) 0 (2) 2
- * 0 0 1 (2) 0 (2) 4 : SDR104 / HS200 / HS400 (4 TAP)
- * 1 0 2 (4) 0 (2) 8
- * 1 0 3 (8) 0 (2) 16
- * 1 0 4 (16) 0 (2) 32
+ * sd_srcfc sd_fc div
+ * stp_hck (div) (div) = sd_srcfc x sd_fc
+ *---------------------------------------------------------
+ * 0 0 (1) 1 (4) 4 : SDR104 / HS200 / HS400 (8 TAP)
+ * 0 1 (2) 1 (4) 8 : SDR50
+ * 1 2 (4) 1 (4) 16 : HS / SDR25
+ * 1 3 (8) 1 (4) 32 : NS / SDR12
+ * 1 4 (16) 1 (4) 64
+ * 0 0 (1) 0 (2) 2
+ * 0 1 (2) 0 (2) 4 : SDR104 / HS200 / HS400 (4 TAP)
+ * 1 2 (4) 0 (2) 8
+ * 1 3 (8) 0 (2) 16
+ * 1 4 (16) 0 (2) 32
*
* NOTE: There is a quirk option to ignore the first row of the dividers
* table when searching for suitable settings. This is because HS400 on
* early ES versions of H3 and M3-W requires a specific setting to work.
*/
static const struct sd_div_table cpg_sd_div_table[] = {
-/* CPG_SD_DIV_TABLE_DATA(stp_hck, stp_ck, sd_srcfc, sd_fc, sd_div) */
- CPG_SD_DIV_TABLE_DATA(0, 0, 0, 1, 4),
- CPG_SD_DIV_TABLE_DATA(0, 0, 1, 1, 8),
- CPG_SD_DIV_TABLE_DATA(1, 0, 2, 1, 16),
- CPG_SD_DIV_TABLE_DATA(1, 0, 3, 1, 32),
- CPG_SD_DIV_TABLE_DATA(1, 0, 4, 1, 64),
- CPG_SD_DIV_TABLE_DATA(0, 0, 0, 0, 2),
- CPG_SD_DIV_TABLE_DATA(0, 0, 1, 0, 4),
- CPG_SD_DIV_TABLE_DATA(1, 0, 2, 0, 8),
- CPG_SD_DIV_TABLE_DATA(1, 0, 3, 0, 16),
- CPG_SD_DIV_TABLE_DATA(1, 0, 4, 0, 32),
+/* CPG_SD_DIV_TABLE_DATA(stp_hck, sd_srcfc, sd_fc, sd_div) */
+ CPG_SD_DIV_TABLE_DATA(0, 0, 1, 4),
+ CPG_SD_DIV_TABLE_DATA(0, 1, 1, 8),
+ CPG_SD_DIV_TABLE_DATA(1, 2, 1, 16),
+ CPG_SD_DIV_TABLE_DATA(1, 3, 1, 32),
+ CPG_SD_DIV_TABLE_DATA(1, 4, 1, 64),
+ CPG_SD_DIV_TABLE_DATA(0, 0, 0, 2),
+ CPG_SD_DIV_TABLE_DATA(0, 1, 0, 4),
+ CPG_SD_DIV_TABLE_DATA(1, 2, 0, 8),
+ CPG_SD_DIV_TABLE_DATA(1, 3, 0, 16),
+ CPG_SD_DIV_TABLE_DATA(1, 4, 0, 32),
};
#define to_sd_clock(_hw) container_of(_hw, struct sd_clock, hw)
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [RFC PATCH] clk: renesas: rcar-gen3: remove stp_ck handling for SDHI
2020-09-14 9:04 [RFC PATCH] clk: renesas: rcar-gen3: remove stp_ck handling for SDHI Wolfram Sang
@ 2020-09-14 9:35 ` Geert Uytterhoeven
2020-09-14 9:53 ` Wolfram Sang
0 siblings, 1 reply; 3+ messages in thread
From: Geert Uytterhoeven @ 2020-09-14 9:35 UTC (permalink / raw)
To: Wolfram Sang; +Cc: linux-clk, Linux-Renesas
Hi Wolfram,
On Mon, Sep 14, 2020 at 11:04 AM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
> There is no case (and none forseen) where we would need to disable the
foreseen
> SDn clock. So, for simplicity, remove its handling.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
>
> One paradigm is to stay minimal and remove unneeded things. Another one
> is to not change working code unnecessarily. I favor the first one a bit
> more, but would understand arguing with the second one.
Indeed.
Does this make the code rely on bootloader setup or reset state?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC PATCH] clk: renesas: rcar-gen3: remove stp_ck handling for SDHI
2020-09-14 9:35 ` Geert Uytterhoeven
@ 2020-09-14 9:53 ` Wolfram Sang
0 siblings, 0 replies; 3+ messages in thread
From: Wolfram Sang @ 2020-09-14 9:53 UTC (permalink / raw)
To: Geert Uytterhoeven; +Cc: linux-clk, Linux-Renesas
[-- Attachment #1: Type: text/plain, Size: 888 bytes --]
On Mon, Sep 14, 2020 at 11:35:07AM +0200, Geert Uytterhoeven wrote:
> Hi Wolfram,
>
> On Mon, Sep 14, 2020 at 11:04 AM Wolfram Sang
> <wsa+renesas@sang-engineering.com> wrote:
> > There is no case (and none forseen) where we would need to disable the
>
> foreseen
Oops, yes.
>
> > SDn clock. So, for simplicity, remove its handling.
> >
> > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> > ---
> >
> > One paradigm is to stay minimal and remove unneeded things. Another one
> > is to not change working code unnecessarily. I favor the first one a bit
> > more, but would understand arguing with the second one.
>
> Indeed.
>
> Does this make the code rely on bootloader setup or reset state?
Before, we wrote '0' or '1' to that bit depending on 'stp_ck'. After
removing 'stp_ck', we unconditionally write 0. So, I think we are safe.
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2020-09-14 9:04 [RFC PATCH] clk: renesas: rcar-gen3: remove stp_ck handling for SDHI Wolfram Sang
2020-09-14 9:35 ` Geert Uytterhoeven
2020-09-14 9:53 ` Wolfram Sang
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