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Message-ID: <5450B485.5050705@intel.com>
Date: Wed, 29 Oct 2014 11:33:57 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: 유한경 <hankyung.yu@....com>,
'Chanho Min' <chanho.min@....com>
CC: 'Chris Ball' <chris@...ntf.net>,
'Ulf Hansson' <ulf.hansson@...aro.org>,
'Seungwon Jeon' <tgih.jun@...sung.com>,
'Jaehoon Chung' <jh80.chung@...sung.com>,
linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
'HyoJun Im' <hyojun.im@....com>, gunho.lee@....com
Subject: Re: [PATCH] mmc:core: fix hs400 timing selection
On 29/10/14 01:30, 유한경 wrote:
> Hi I'm Hankyung Yu
>
> I will answer instead Chanho Min
>
> HS200 mode right thing to support less than 52Mhz
>
> However CLK <-> DATA delay timing is dependent on the clock.
>
> So only lower clock without adjusting the timing and mode of a control h/w
> ever the problem may occur.
>
> So change the operating mode and to lower the clock.
I meant something different.
With your patch I find that __mmc_switch() -> send_status() fails.
So I suggest something like this:
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 92247c2..195d48a 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1045,21 +1045,28 @@ static int mmc_select_hs400(struct mmc_card *card)
err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
EXT_CSD_HS_TIMING, EXT_CSD_TIMING_HS,
card->ext_csd.generic_cmd6_time,
- true, true, true);
+ true, false, false);
+ if (!err) {
+ u32 status;
+
+ /*
+ * According to JEDEC v5.01 spec (6.6.5), Clock frequency should
+ * be set to a value not greater than 52MHz after the HS_TIMING
+ * field is set to 0x1.
+ */
+ mmc_set_timing(card->host, MMC_TIMING_MMC_HS);
+ mmc_set_bus_speed(card);
+
+ err = __mmc_send_status(card, &status, false, 1);
+ if (!err)
+ err = mmc_check_switch_status(card->host, status);
+ }
if (err) {
pr_err("%s: switch to high-speed from hs200 failed, err:%d\n",
mmc_hostname(host), err);
return err;
}
- /*
- * According to JEDEC v5.01 spec (6.6.5), Clock frequency should
- * be set to a value not greater than 52MHz after the HS_TIMING
- * field is set to 0x1.
- */
- mmc_set_timing(card->host, MMC_TIMING_MMC_HS);
- mmc_set_bus_speed(card);
-
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
EXT_CSD_BUS_WIDTH,
EXT_CSD_DDR_BUS_WIDTH_8,
diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
index 23aa3a3..f917527 100644
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -23,15 +23,12 @@
#define MMC_OPS_TIMEOUT_MS (10 * 60 * 1000) /* 10 minute timeout */
-static inline int __mmc_send_status(struct mmc_card *card, u32 *status,
- bool ignore_crc)
+int __mmc_send_status(struct mmc_card *card, u32 *status, bool ignore_crc,
+ int retries)
{
int err;
struct mmc_command cmd = {0};
- BUG_ON(!card);
- BUG_ON(!card->host);
-
cmd.opcode = MMC_SEND_STATUS;
if (!mmc_host_is_spi(card->host))
cmd.arg = card->rca << 16;
@@ -39,7 +36,7 @@ static inline int __mmc_send_status(struct mmc_card *card, u32 *status,
if (ignore_crc)
cmd.flags &= ~MMC_RSP_CRC;
- err = mmc_wait_for_cmd(card->host, &cmd, MMC_CMD_RETRIES);
+ err = mmc_wait_for_cmd(card->host, &cmd, retries);
if (err)
return err;
@@ -54,7 +51,7 @@ static inline int __mmc_send_status(struct mmc_card *card, u32 *status,
int mmc_send_status(struct mmc_card *card, u32 *status)
{
- return __mmc_send_status(card, status, false);
+ return __mmc_send_status(card, status, false, MMC_CMD_RETRIES);
}
static int _mmc_select_card(struct mmc_host *host, struct mmc_card *card)
@@ -419,6 +416,21 @@ int mmc_spi_set_crc(struct mmc_host *host, int use_crc)
return err;
}
+int mmc_check_switch_status(struct mmc_host *host, u32 status)
+{
+ if (mmc_host_is_spi(host)) {
+ if (status & R1_SPI_ILLEGAL_COMMAND)
+ return -EBADMSG;
+ } else {
+ if (status & 0xFDFFA000)
+ pr_warn("%s: unexpected status %#x after switch\n",
+ mmc_hostname(host), status);
+ if (status & R1_SWITCH_ERROR)
+ return -EBADMSG;
+ }
+ return 0;
+}
+
/**
* __mmc_switch - modify EXT_CSD register
* @card: the MMC card associated with the data transfer
@@ -497,7 +509,7 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
timeout = jiffies + msecs_to_jiffies(timeout_ms);
do {
if (send_status) {
- err = __mmc_send_status(card, &status, ignore_crc);
+ err = __mmc_send_status(card, &status, ignore_crc, 1);
if (err)
return err;
}
@@ -524,18 +536,7 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
}
} while (R1_CURRENT_STATE(status) == R1_STATE_PRG);
- if (mmc_host_is_spi(host)) {
- if (status & R1_SPI_ILLEGAL_COMMAND)
- return -EBADMSG;
- } else {
- if (status & 0xFDFFA000)
- pr_warn("%s: unexpected status %#x after switch\n",
- mmc_hostname(host), status);
- if (status & R1_SWITCH_ERROR)
- return -EBADMSG;
- }
-
- return 0;
+ return mmc_check_switch_status(host, status);
}
EXPORT_SYMBOL_GPL(__mmc_switch);
diff --git a/drivers/mmc/core/mmc_ops.h b/drivers/mmc/core/mmc_ops.h
index 6f4b00e..a59319c 100644
--- a/drivers/mmc/core/mmc_ops.h
+++ b/drivers/mmc/core/mmc_ops.h
@@ -20,7 +20,10 @@ int mmc_send_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr);
int mmc_all_send_cid(struct mmc_host *host, u32 *cid);
int mmc_set_relative_addr(struct mmc_card *card);
int mmc_send_csd(struct mmc_card *card, u32 *csd);
+int __mmc_send_status(struct mmc_card *card, u32 *status, bool ignore_crc,
+ int retries);
int mmc_send_status(struct mmc_card *card, u32 *status);
+int mmc_check_switch_status(struct mmc_host *host, u32 status);
int mmc_send_cid(struct mmc_host *host, u32 *cid);
int mmc_spi_read_ocr(struct mmc_host *host, int highcap, u32 *ocrp);
int mmc_spi_set_crc(struct mmc_host *host, int use_crc);
>
>
> -----Original Message-----
> From: Adrian Hunter [mailto:adrian.hunter@...el.com]
> Sent: Tuesday, October 28, 2014 10:24 PM
> To: Chanho Min
> Cc: Chris Ball; Ulf Hansson; Seungwon Jeon; Jaehoon Chung; linux-
> mmc@...r.kernel.org; linux-kernel@...r.kernel.org; HyoJun Im; gunho.lee@....
> com; Hankyung Yu
> Subject: Re: [PATCH] mmc:core: fix hs400 timing selection
>
> On 22/10/14 05:55, Chanho Min wrote:
>> According to JEDEC v5.01 spec (6.6.5), In order to switch to HS400
>> mode, host should perform the following steps.
>>
>> 1. HS200 mode selection completed
>> 2. Set HS_TIMING to 0x01(High Speed)
>> 3. Host changes frequency to =< 52MHz 4. Set the bus width to DDR
>> 8bit (CMD6) 5. Host may read Driver Strength (CMD8) 6. Set HS_TIMING
>> to 0x03 (HS400)
>>
>> In current implementation, the order of 2 and 3 is reversed.
>
> But HS200 mode supports running at speeds less than 52 MHz whereas High
> Speed mode does not support running at speeds greater than
> 52 MHz.
>
> So the switch command might succeed, but the subsequent send_status command
> (see __mmc_switch) could be expected to fail unless the frequency is
> changed first.
>
>> The HS_TIMING field should be set to 0x1 before the clock frequency is
>> set to a value not greater than 52 MHz. Otherwise, Initialization of
>> timing can be failed. Also, the host contoller's UHS timing mode
>> should be set to DDR50 after the bus width is set to DDR 8bit.
>>
>> Signed-off-by: Hankyung Yu <hankyung.yu@....com>
>> Signed-off-by: Chanho Min <chanho.min@....com>
>> ---
>> drivers/mmc/core/mmc.c | 13 ++++++++++---
>> 1 file changed, 10 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index
>> a301a78..52f78e0 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -1061,9 +1061,6 @@ static int mmc_select_hs400(struct mmc_card *card)
>> * Before switching to dual data rate operation for HS400,
>> * it is required to convert from HS200 mode to HS mode.
>> */
>> - mmc_set_timing(card->host, MMC_TIMING_MMC_HS);
>> - mmc_set_bus_speed(card);
>> -
>> err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> EXT_CSD_HS_TIMING, EXT_CSD_TIMING_HS,
>> card->ext_csd.generic_cmd6_time, @@ -1074,6
> +1071,14 @@ static
>> int mmc_select_hs400(struct mmc_card *card)
>> return err;
>> }
>>
>> + /*
>> + * According to JEDEC v5.01 spec (6.6.5), Clock frequency should
>> + * be set to a value not greater than 52MHz after the HS_TIMING
>> + * field is set to 0x1.
>> + */
>> + mmc_set_timing(card->host, MMC_TIMING_MMC_HS);
>> + mmc_set_bus_speed(card);
>> +
>> err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> EXT_CSD_BUS_WIDTH,
>> EXT_CSD_DDR_BUS_WIDTH_8,
>> @@ -1084,6 +1089,8 @@ static int mmc_select_hs400(struct mmc_card *card)
>> return err;
>> }
>>
>> + mmc_set_timing(card->host, MMC_TIMING_MMC_DDR52);
>> +
>> err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> EXT_CSD_HS_TIMING, EXT_CSD_TIMING_HS400,
>> card->ext_csd.generic_cmd6_time,
>>
>
>
>
--
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