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Message-ID: <81bf38cd-b6a4-4a6f-a51d-bc916e3b8f96@intel.com>
Date: Tue, 3 Oct 2023 18:02:24 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Ulf Hansson <ulf.hansson@...aro.org>
Cc: Victor Shih <victorshihgli@...il.com>, linux-mmc@...r.kernel.org,
linux-kernel@...r.kernel.org, benchuanggli@...il.com,
HL.Liu@...esyslogic.com.tw, Greg.tu@...esyslogic.com.tw,
takahiro.akashi@...aro.org, dlunev@...omium.org,
Ben Chuang <ben.chuang@...esyslogic.com.tw>,
Victor Shih <victor.shih@...esyslogic.com.tw>
Subject: Re: [PATCH V12 10/23] mmc: sdhci-uhs2: add reset function and
uhs2_mode function
On 3/10/23 15:22, Ulf Hansson wrote:
> On Tue, 3 Oct 2023 at 13:37, Adrian Hunter <adrian.hunter@...el.com> wrote:
>>
>> On 3/10/23 13:30, Ulf Hansson wrote:
>>> On Fri, 15 Sept 2023 at 11:44, Victor Shih <victorshihgli@...il.com> wrote:
>>>>
>>>> From: Victor Shih <victor.shih@...esyslogic.com.tw>
>>>>
>>>> Sdhci_uhs2_reset() does a UHS-II specific reset operation.
>>>>
>>>> Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
>>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
>>>> Signed-off-by: Victor Shih <victor.shih@...esyslogic.com.tw>
>>>> Acked-by: Adrian Hunter <adrian.hunter@...el.com>
>>>> ---
>>>>
>>>> Updates in V8:
>>>> - Adjust the position of matching brackets.
>>>>
>>>> Updates in V6:
>>>> - Remove unnecessary functions and simplify code.
>>>>
>>>> ---
>>>>
>>>> drivers/mmc/host/sdhci-uhs2.c | 45 +++++++++++++++++++++++++++++++++++
>>>> drivers/mmc/host/sdhci-uhs2.h | 2 ++
>>>> 2 files changed, 47 insertions(+)
>>>>
>>>> diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
>>>> index e339821d3504..dfc80a7f1bad 100644
>>>> --- a/drivers/mmc/host/sdhci-uhs2.c
>>>> +++ b/drivers/mmc/host/sdhci-uhs2.c
>>>> @@ -10,7 +10,9 @@
>>>> * Author: AKASHI Takahiro <takahiro.akashi@...aro.org>
>>>> */
>>>>
>>>> +#include <linux/delay.h>
>>>> #include <linux/module.h>
>>>> +#include <linux/iopoll.h>
>>>>
>>>> #include "sdhci.h"
>>>> #include "sdhci-uhs2.h"
>>>> @@ -49,6 +51,49 @@ void sdhci_uhs2_dump_regs(struct sdhci_host *host)
>>>> }
>>>> EXPORT_SYMBOL_GPL(sdhci_uhs2_dump_regs);
>>>>
>>>> +/*****************************************************************************\
>>>> + * *
>>>> + * Low level functions *
>>>> + * *
>>>> +\*****************************************************************************/
>>>> +
>>>> +bool sdhci_uhs2_mode(struct sdhci_host *host)
>>>> +{
>>>> + return host->mmc->flags & MMC_UHS2_SUPPORT;
>>>
>>> The MMC_UHS2_SUPPORT bit looks redundant to me. Instead, I think we
>>> should be using mmc->ios.timings, which already indicates whether we
>>> are using UHS2 (MMC_TIMING_UHS2_SPEED_*). See patch2 where we added
>>> this.
>>>
>>> That said, I think we should drop the sdhci_uhs2_mode() function
>>> altogether and instead use mmc_card_uhs2(), which means we should move
>>> it to include/linux/mmc/host.h, so it becomes available for host
>>> drivers.
>>>
>>
>> UHS2 mode starts at UHS2 initialization and ends either when UHS2
>> initialization fails, or the card is removed.
>>
>> So it includes re-initialization and reset when the transfer mode
>> currently transitions through MMC_TIMING_LEGACY.
>>
>> So mmc_card_uhs2() won't work correctly for the host callbacks
>> unless something is done about that.
>
> Right, thanks for clarifying!
>
> In that case I wonder if we couldn't change the way we update the
> ->ios.timing for UHS2. It seems silly to have two (similar) ways to
> indicate that we have moved to UHS2.
Perhaps something like below:
diff --git a/drivers/mmc/core/sd_uhs2.c b/drivers/mmc/core/sd_uhs2.c
index aacefdd6bc9e..e39d63d46041 100644
--- a/drivers/mmc/core/sd_uhs2.c
+++ b/drivers/mmc/core/sd_uhs2.c
@@ -70,7 +70,8 @@ static int sd_uhs2_power_off(struct mmc_host *host)
host->ios.vdd = 0;
host->ios.clock = 0;
- host->ios.timing = MMC_TIMING_LEGACY;
+ /* Must set UHS2 timing to identify UHS2 mode */
+ host->ios.timing = MMC_TIMING_UHS2_SPEED_A;
host->ios.power_mode = MMC_POWER_OFF;
if (host->flags & MMC_UHS2_SD_TRAN)
host->flags &= ~MMC_UHS2_SD_TRAN;
@@ -1095,7 +1096,8 @@ static void sd_uhs2_detect(struct mmc_host *host)
mmc_claim_host(host);
mmc_detach_bus(host);
sd_uhs2_power_off(host);
- host->flags &= ~MMC_UHS2_SUPPORT;
+ /* Remove UHS2 timing to indicate the end of UHS2 mode */
+ host->ios.timing = MMC_TIMING_LEGACY;
mmc_release_host(host);
}
}
@@ -1338,7 +1340,8 @@ static int sd_uhs2_attach(struct mmc_host *host)
err:
mmc_detach_bus(host);
sd_uhs2_power_off(host);
- host->flags &= ~MMC_UHS2_SUPPORT;
+ /* Remove UHS2 timing to indicate the end of UHS2 mode */
+ host->ios.timing = MMC_TIMING_LEGACY;
return err;
}
diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
index 517c497112f4..d1f3318b7d3a 100644
--- a/drivers/mmc/host/sdhci-uhs2.c
+++ b/drivers/mmc/host/sdhci-uhs2.c
@@ -267,10 +267,11 @@ static void __sdhci_uhs2_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
/* UHS2 timing. Note, UHS2 timing is disabled when powering off */
ctrl_2 = sdhci_readw(host, SDHCI_HOST_CONTROL2);
- if (ios->timing == MMC_TIMING_UHS2_SPEED_A ||
- ios->timing == MMC_TIMING_UHS2_SPEED_A_HD ||
- ios->timing == MMC_TIMING_UHS2_SPEED_B ||
- ios->timing == MMC_TIMING_UHS2_SPEED_B_HD)
+ if (ios->power_mode != MMC_POWER_OFF &&
+ (ios->timing == MMC_TIMING_UHS2_SPEED_A ||
+ ios->timing == MMC_TIMING_UHS2_SPEED_A_HD ||
+ ios->timing == MMC_TIMING_UHS2_SPEED_B ||
+ ios->timing == MMC_TIMING_UHS2_SPEED_B_HD))
ctrl_2 |= SDHCI_CTRL_UHS2 | SDHCI_CTRL_UHS2_ENABLE;
else
ctrl_2 &= ~(SDHCI_CTRL_UHS2 | SDHCI_CTRL_UHS2_ENABLE);
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