[PATCH] mmc: sd: Remove the patch that fix signal voltage when there is no power cycle

[Seunghui Lee <sh043.lee@samsung.com>]

At first, all error flow of mmc_set_uhs_voltage() has power cycle
except R1_ERROR and no start_signal_voltage_switch() func pointer.

There is the performance regression issue of SDR104 SD card from
the market VOC. Normally, once a SDR104 SD card fails to switch voltage,
it works HS mode.
And then it initializes SDR104 mode after system resume or error handling.

However, with below patch,
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/mmc/core/sd.c?id=6a11fc47f175c8d87018e89cb58e2d36c66534cb
Once a SD card does, it initializes SDR25 mode forever
after system resume or error handling(re-initialized).
Host updates sd3_bus_mode by calling mmc_read_switch(),
the value of sd3_bus_mode doesn't set for SDR104, SDR50 and DDR50 mode.

So, if host doesn't update sd3_bus_mode,
the SD card works SDR104 mode after system resume or error-handling.

Here is an example.

AS-IS : test log
// normal case : sd3_bus_mode = 0x1F, sd_bus_speed = SDR104, clock 208MHz
[  111.907789] [1:    kworker/1:3:  772] [TEST] mmc_sd_init_card: 1119: caps=0x407f020f, sd3_bus_mode=0x1f, v18_fixup_failed false, signal_voltage =0x1.
[  111.907824] [1:    kworker/1:3:  772] [TEST] mmc_sd_init_card: 1149: rocr 0xc1ff8000, S18A, uhs.
[  111.908707] [1:    kworker/1:3:  772] [TEST] sd_update_bus_speed_mode: caps 0x407f020f, sd3_bus_mode = 0x1f, sd_bus_speed = 3, card->ocr = 0x40000.
[  111.912484] [1:    kworker/1:3:  772] [TEST] sd_set_bus_speed_mode: sd_bus_speed=3, timing=6, uhs_max_dtr=208000000, card->ocr=0x40000.
// resume : issue occurs : SDcard doesn't release busy for checking 10 times
[  112.096550] [5:    kworker/5:2:  207] [TEST] mmc_sd_init_card: 1040: card->ocr 0x40000.
[  112.096560] [5:    kworker/5:2:  207] [TEST] mmc_sd_get_cid: ocr 0x40000(pocr 0x40000), retries 10.
...
[  114.531129] [5:    kworker/5:2:  207] [TEST] mmc_power_cycle.
[  114.579500] [5:    kworker/5:2:  207] [TEST] mmc_sd_get_cid: ocr 0x41040000(pocr 0x40000), retries 0.
[  114.579506] [5:    kworker/5:2:  207] mmc0: Skipping voltage switch
[  114.757575] [5:    kworker/5:2:  207] [TEST] mmc_sd_init_card: 1119: caps=0x407f020f, sd3_bus_mode=0x1f, v18_fixup_failed false, signal_voltage =0x0.
[  114.757583] [5:    kworker/5:2:  207] [TEST] mmc_sd_init_card: 1128: switch with oldcard.
[  114.759742] [5:    kworker/5:2:  207] [TEST] mmc_read_switch: sd_switch ret 0, sd3_bus_mode=3.
// sd3_bus_mode = 0x3 supports HS, SDR25 and SDR12
[  114.759750] [5:    kworker/5:2:  207] [TEST] mmc_sd_init_card: 1157: switch hs.
// next resume : the SDcard initializes to SDR25(HS) mode(sd_bus_speed = 1) by sd3_bus_mode setting with clk 50MHz
[  114.968346] [5:    kworker/5:2:  207] [TEST] mmc_sd_init_card: 1040: card->ocr 0x40000.
[  114.968359] [5:    kworker/5:2:  207] [TEST] mmc_sd_get_cid: ocr 0x40000(pocr 0x40000), retries 10.
[  115.167346] [5:    kworker/5:2:  207] [TEST] mmc_sd_init_card: 1119: caps=0x407f020f, sd3_bus_mode=0x3, v18_fixup_failed false, signal_voltage =0x1.
[  115.167366] [5:    kworker/5:2:  207] [TEST] mmc_sd_init_card: 1149: rocr 0xc1ff8000, S18A, uhs.
[  115.168041] [5:    kworker/5:2:  207] [TEST] mmc_sd_init_uhs_card: before update: caps 0x407f020f, sd3_bus_mode = 3, sd_bus_speed = 3, card->ocr = 0x40000.
[  115.168051] [5:    kworker/5:2:  207] [TEST] sd_update_bus_speed_mode: caps 0x407f020f, sd3_bus_mode = 3, sd_bus_speed = 1, card->ocr = 0x40000.
[  115.169176] [5:    kworker/5:2:  207] [TEST] sd_set_bus_speed_mode: sd_bus_speed=1, timing=4, uhs_max_dtr=50000000, card->ocr=0x40000.

TO-BE : TEST log with this commit
// resume : issue occurs : SDcard doesn't release busy for checking 10 times
[ 1843.594805] [4:    kworker/4:5:21512] [TEST] mmc_sd_get_cid: ocr 0x41040000(pocr 0x40000), retries 0.
[ 1843.594812] [4:    kworker/4:5:21512] mmc0: Skipping voltage switch
[ 1843.772555] [4:    kworker/4:5:21512] [TEST] mmc_sd_init_card: 1122: caps=0x407f020f, sd3_bus_mode=0x1f, v18_fixup_failed false, signal_voltage =0x0.
// no update sd3_bus_mode value
[ 1843.772563] [4:    kworker/4:5:21512] [TEST] mmc_sd_init_card: 1164: switch hs.
// next resume : the SDcard initializes to SDR104
[ 1844.191295] [5:   kworker/5:93: 2282] [TEST] mmc_sd_init_card: 1122: caps=0x407f020f, sd3_bus_mode=0x1f, v18_fixup_failed false, signal_voltage =0x1.
[ 1844.191315] [5:   kworker/5:93: 2282] [TEST] mmc_sd_init_card: 1154: rocr 0xc1ff8000, S18A, uhs.
[ 1844.192175] [5:   kworker/5:93: 2282] [TEST] mmc_sd_init_uhs_card: before update: caps 0x407f020f, sd3_bus_mode = 0x1f, sd_bus_speed = 3, card->ocr = 0x40000.
[ 1844.192187] [5:   kworker/5:93: 2282] [TEST] sd_update_bus_speed_mode: caps 0x407f020f, sd3_bus_mode = 0x1f, sd_bus_speed = 3, card->ocr = 0x40000.
[ 1844.198697] [5:   kworker/5:93: 2282] [TEST] sd_set_bus_speed_mode: sd_bus_speed=3, timing=6, uhs_max_dtr=208000000, card->ocr=0x40000.

Signed-off-by: Seunghui Lee <sh043.lee@samsung.com>
Tested-by: DooHyun Hwang <dh0421.hwang@samsung.com>
---
 drivers/mmc/core/sd.c | 47 ++-----------------------------------------
 1 file changed, 2 insertions(+), 45 deletions(-)

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index cee4c0b59f43..4e3d39956185 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -1001,18 +1001,6 @@ unsigned mmc_sd_get_max_clock(struct mmc_card *card)
 	return max_dtr;
 }
 
-static bool mmc_sd_card_using_v18(struct mmc_card *card)
-{
-	/*
-	 * According to the SD spec., the Bus Speed Mode (function group 1) bits
-	 * 2 to 4 are zero if the card is initialized at 3.3V signal level. Thus
-	 * they can be used to determine if the card has already switched to
-	 * 1.8V signaling.
-	 */
-	return card->sw_caps.sd3_bus_mode &
-	       (SD_MODE_UHS_SDR50 | SD_MODE_UHS_SDR104 | SD_MODE_UHS_DDR50);
-}
-
 static int sd_write_ext_reg(struct mmc_card *card, u8 fno, u8 page, u16 offset,
 			    u8 reg_data)
 {
@@ -1400,10 +1388,9 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
 	int err;
 	u32 cid[4];
 	u32 rocr = 0;
-	bool v18_fixup_failed = false;
 
 	WARN_ON(!host->claimed);
-retry:
+
 	err = mmc_sd_get_cid(host, ocr, cid, &rocr);
 	if (err)
 		return err;
@@ -1472,36 +1459,6 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
 	if (err)
 		goto free_card;
 
-	/*
-	 * If the card has not been power cycled, it may still be using 1.8V
-	 * signaling. Detect that situation and try to initialize a UHS-I (1.8V)
-	 * transfer mode.
-	 */
-	if (!v18_fixup_failed && !mmc_host_is_spi(host) && mmc_host_uhs(host) &&
-	    mmc_sd_card_using_v18(card) &&
-	    host->ios.signal_voltage != MMC_SIGNAL_VOLTAGE_180) {
-		/*
-		 * Re-read switch information in case it has changed since
-		 * oldcard was initialized.
-		 */
-		if (oldcard) {
-			err = mmc_read_switch(card);
-			if (err)
-				goto free_card;
-		}
-		if (mmc_sd_card_using_v18(card)) {
-			if (mmc_host_set_uhs_voltage(host) ||
-			    mmc_sd_init_uhs_card(card)) {
-				v18_fixup_failed = true;
-				mmc_power_cycle(host, ocr);
-				if (!oldcard)
-					mmc_remove_card(card);
-				goto retry;
-			}
-			goto done;
-		}
-	}
-
 	/* Initialization sequence for UHS-I cards */
 	if (rocr & SD_ROCR_S18A && mmc_host_uhs(host)) {
 		err = mmc_sd_init_uhs_card(card);
@@ -1566,7 +1523,7 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
 		err = -EINVAL;
 		goto free_card;
 	}
-done:
+
 	host->card = card;
 	return 0;
 
-- 
2.29.0