Re: [PATCH V2 02/12] pinctrl: tegra: add suspend and resume support

Sowjanya Komatineni <skomatineni@xxxxxxxxxx> · Wed, 29 May 2019 14:07:59 -0700

On 5/29/19 1:56 PM, Sowjanya Komatineni wrote:

On 5/29/19 1:47 PM, Dmitry Osipenko wrote:
29.05.2019 23:11, Sowjanya Komatineni пишет:
On 5/29/19 12:32 PM, Dmitry Osipenko wrote:
29.05.2019 21:14, Sowjanya Komatineni пишет:
On 5/29/19 8:29 AM, Dmitry Osipenko wrote:
29.05.2019 2:08, Sowjanya Komatineni пишет:
This patch adds suspend and resume support for Tegra pinctrl driver
and registers them to syscore so the pinmux settings are restored
before the devices resume.

Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
---
    drivers/pinctrl/tegra/pinctrl-tegra.c    | 68
+++++++++++++++++++++++++++++++-
    drivers/pinctrl/tegra/pinctrl-tegra.h    |  3 ++
    drivers/pinctrl/tegra/pinctrl-tegra114.c |  1 +
    drivers/pinctrl/tegra/pinctrl-tegra124.c |  1 +
    drivers/pinctrl/tegra/pinctrl-tegra20.c  |  1 +
    drivers/pinctrl/tegra/pinctrl-tegra210.c |  1 +
    drivers/pinctrl/tegra/pinctrl-tegra30.c  |  1 +
    7 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/drivers/pinctrl/tegra/pinctrl-tegra.c
b/drivers/pinctrl/tegra/pinctrl-tegra.c
index a5008c066bac..bdc47e62c457 100644
--- a/drivers/pinctrl/tegra/pinctrl-tegra.c
+++ b/drivers/pinctrl/tegra/pinctrl-tegra.c
@@ -28,11 +28,18 @@
    #include <linux/pinctrl/pinmux.h>
    #include <linux/pinctrl/pinconf.h>
    #include <linux/slab.h>
+#include <linux/syscore_ops.h>
      #include "../core.h"
    #include "../pinctrl-utils.h"
    #include "pinctrl-tegra.h"
    +#define EMMC2_PAD_CFGPADCTRL_0            0x1c8
+#define EMMC4_PAD_CFGPADCTRL_0            0x1e0
+#define EMMC_DPD_PARKING            (0x1fff << 14)
+
+static struct tegra_pmx *pmx;
+
    static inline u32 pmx_readl(struct tegra_pmx *pmx, u32 bank, 
u32
reg)
    {
        return readl(pmx->regs[bank] + reg);
@@ -629,6 +636,50 @@ static void
tegra_pinctrl_clear_parked_bits(struct tegra_pmx *pmx)
        }
    }
    +static int __maybe_unused tegra_pinctrl_suspend(void)
+{
+    u32 *backup_regs = pmx->backup_regs;
+    u32 *regs;
+    int i, j;
+
+    for (i = 0; i < pmx->nbanks; i++) {
+        regs = pmx->regs[i];
+        for (j = 0; j < pmx->reg_bank_size[i] / 4; j++)
+            *backup_regs++ = readl(regs++);
+    }
+
+    return pinctrl_force_sleep(pmx->pctl);
+}
+
+static void __maybe_unused tegra_pinctrl_resume(void)
+{
+    u32 *backup_regs = pmx->backup_regs;
+    u32 *regs;
+    u32 val;
+    int i, j;
+
+    for (i = 0; i < pmx->nbanks; i++) {
+        regs = pmx->regs[i];
+        for (j = 0; j < pmx->reg_bank_size[i] / 4; j++)
+            writel(*backup_regs++, regs++);
+    }
+
+    if (pmx->soc->has_park_padcfg) {
+        val = pmx_readl(pmx, 0, EMMC2_PAD_CFGPADCTRL_0);
+        val &= ~EMMC_DPD_PARKING;
+        pmx_writel(pmx, val, 0, EMMC2_PAD_CFGPADCTRL_0);
+
+        val = pmx_readl(pmx, 0, EMMC4_PAD_CFGPADCTRL_0);
+        val &= ~EMMC_DPD_PARKING;
+        pmx_writel(pmx, val, 0, EMMC4_PAD_CFGPADCTRL_0);
+    }
+}

But the CFGPADCTRL registers are already programmed by restoring the
backup_regs and hence the relevant EMMC's are already unparked. 
Hence
why do you need to force-unpark both of the EMMC's? What if EMMC is
unpopulated on a board, why do you need to unpark it then?
PARK bit for EMMC2/EMMC4 (EMMC2_PAD_CFGPADCTRL and 
EMMC4_PAD_CFGPADCTRL)
are not part of pinmux.

They are part of CFGPADCTRL register so pinctrl driver pingroup 
doesn't
include these registers.
I'm looking at the tegra210_groups and it clearly has these both
registers as a part of pinctrl setup because the rest of the bits
configure drive of the pads.

  From pinctrl-tegra210.c:

#define DRV_PINGROUP_REG_A        0x8d4    /* bank 0 */

DRV_PINGROUP(sdmmc2, 0xa9c, 2,  6,  8,  6,  28, 2,  30, 2),
DRV_PINGROUP(sdmmc4, 0xab4, 2,  6,  8,  6,  28, 2,  30, 2),

...

0xa9c - 0x8d4 = 0x1c8
0xab4 - 0x8d4 = 0x1e0

Hence the PARK bits are already getting unset by restoring the
backup_regs because the CFGPADCTRL registers are a part of the 
"bank 0"
registers.

Am I still missing something?
DRV_PINGROUP parked_bit is -1 and will not be programmed so store and
restore will not take care of it.

Also EMMC PADCFG is the only padcfg register which has parked bit and
for other IO pads its part of pinmux
You're storing raw values of all of the PINCTRL registers and then
restoring the raw values (if I'm not misreading that part on the patch),
it's absolutely meaningless that DRV_PINGROUP doesn't define the PARK 
bits.

In a result, the backup_regs array contains raw CFGPADCTRL value with
the PARK bits being unset on store, that value is written out on the
restore as-is and hence the PARK bits are getting unset as well.

And why DRV_PINGROUP misses PARK bits for the EMMC's? Looks like a
driver's drawback that need to be addressed.

Parked bits from padcfg are available only for couple of EMMC registers.

default PARK bits are set so stored value contains park bit set. on 
resume, after restoring park bit is cleared.

on subsequence DPD entry, stored value contains park bit 0 and HW 
clamps park bit to logic 1 during DPD entry and cleared again on resume.


Other IOs park bit in pinmux gets cleared thru 
tegra_pinctrl_clear_parked_bits on probe and during suspend register 
values saved contains park bit = 0 which is same when restored on DPD 
resume.

clearing park bit during resume for EMMC pads is same as clearing it 
during probe which is then saved during suspend and restored on resume 
similar to pinmux registers.

So for more readability, probably can clear parked bit for EMMC during 
pinctrl_clear_parked_bits instead of on resume.








