Hi Jerome,
we have the known issue that the latest next kernel still fails on
Odroid C2 with a 128GB eMMC card (w/o adjusting the initial tx phase).
I found the time to dig a little deeper into it and reason is that
there are certain rx/tx phase combinations which are perfectly fine
when tuning but fail in real life.
Don't ask me how this can happen, I just see it happen.
To deal with such cases I added some code to avoid known invalid phase
values when retuning. In addition I added some code to deal with the
following (more or less corner) case:
Let's say we have rx = 0° and tx = 0° and working is only combination
rx = 180° and tx = 180°.
Then just tuning rx only or tx only will never result in a working
combination.
Following patch makes my system work. I just see one CRC error when
the initally tuned rx/tx phase combination fails and then the
retuning results in a stable system w/o further errors.
I'd appreciate if you could check that this patch doesn't break any
of your systems.
Rgds, Heiner
---
drivers/mmc/host/meson-gx-mmc.c | 29 ++++++++++++++++++++++-------
1 file changed, 22 insertions(+), 7 deletions(-)
diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index 85745ef1..95cb439d 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -120,6 +120,7 @@
#define SD_EMMC_DESC_CHAIN_MODE BIT(1)
#define MUX_CLK_NUM_PARENTS 2
+#define MAX_TUNING_ATTEMPTS 10
struct sd_emmc_desc {
u32 cmd_cfg;
@@ -687,15 +688,23 @@ static int meson_mmc_find_tuning_point(unsigned long *test)
static int meson_mmc_clk_phase_tuning(struct mmc_host *mmc, u32 opcode,
struct clk *clk)
{
- int point, ret;
+ int point, ret, old_phase;
DECLARE_BITMAP(test, CLK_PHASE_POINT_NUM);
+ old_phase = clk_get_phase(clk);
+ if (old_phase < 0)
+ return old_phase;
+
dev_dbg(mmc_dev(mmc), "%s phase/delay tunning...\n",
__clk_get_name(clk));
bitmap_zero(test, CLK_PHASE_POINT_NUM);
/* Explore tuning points */
for (point = 0; point < CLK_PHASE_POINT_NUM; point++) {
+ /* when retuning avoid the surrounding of where we failed */
+ if (mmc->doing_retune)
+ if (abs(point * CLK_PHASE_STEP - old_phase) <= 45)
+ continue;
clk_set_phase(clk, point * CLK_PHASE_STEP);
ret = mmc_send_tuning(mmc, opcode, NULL);
if (!ret)
@@ -704,8 +713,11 @@ static int meson_mmc_clk_phase_tuning(struct mmc_host *mmc, u32 opcode,
/* Find the optimal tuning point and apply it */
point = meson_mmc_find_tuning_point(test);
- if (point < 0)
+ if (point < 0) {
+ /* prevent from getting stuck if we failed */
+ clk_set_phase(clk, (old_phase + 90) % 360);
return point; /* tuning failed */
+ }
clk_set_phase(clk, point * CLK_PHASE_STEP);
dev_dbg(mmc_dev(mmc), "success with phase: %d\n",
@@ -716,7 +728,7 @@ static int meson_mmc_clk_phase_tuning(struct mmc_host *mmc, u32 opcode,
static int meson_mmc_execute_tuning(struct mmc_host *mmc, u32 opcode)
{
struct meson_host *host = mmc_priv(mmc);
- int ret;
+ int i, ret;
/*
* If this is the initial tuning, try to get a sane Rx starting
@@ -729,11 +741,14 @@ static int meson_mmc_execute_tuning(struct mmc_host *mmc, u32 opcode)
return ret;
}
- ret = meson_mmc_clk_phase_tuning(mmc, opcode, host->tx_clk);
- if (ret)
- return ret;
+ for (i = 0; i < MAX_TUNING_ATTEMPTS; i++) {
+ meson_mmc_clk_phase_tuning(mmc, opcode, host->tx_clk);
+ ret = meson_mmc_clk_phase_tuning(mmc, opcode, host->rx_clk);
+ if (!ret)
+ return 0;
+ }
- return meson_mmc_clk_phase_tuning(mmc, opcode, host->rx_clk);
+ return ret;
}
static void meson_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
--
2.14.2
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