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[PATCH v5 0/5] Add enhanced strobe support for emmc version 5.1 or later

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  [PATCH v5 0/5] Add enhanced strobe support for emmc version 5.1 or later Shawn Lin <shawn.lin@rock-chips.com> - 2016-05-23 06:20 +0200
    [PATCH v5 2/5] mmc: core: add mmc-hs400-enhanced-strobe support Shawn Lin <shawn.lin@rock-chips.com> - 2016-05-23 06:20 +0200
      Re: [PATCH v5 2/5] mmc: core: add mmc-hs400-enhanced-strobe support Doug Anderson <dianders@chromium.org> - 2016-05-23 23:00 +0200
      Re: [PATCH v5 2/5] mmc: core: add mmc-hs400-enhanced-strobe support Jaehoon Chung <jh80.chung@samsung.com> - 2016-05-24 12:30 +0200

#1405088 — [PATCH v5 0/5] Add enhanced strobe support for emmc version 5.1 or later

Hello all,

This patch is going to support enhanced strobe function
for emmc version 5.1+ introduced by JEDEC recently.

Enchanced strobe is a optional function, so we add a new cap* for drivers to
decide whether to use it.

When introduing hs400 mode, JEDEC asks controllers to use data strobe line
to latch the data from emmc devives. But for cmd-reponse, not mentioned yet.
Since emmc version 5.1 published, JEDEC adds enhanced strobe function to deal
with cmd-response the same way as data-read. This feature is optional.

From the spec(section 6.6.2.3), the standard scenario to select HS400 enhanced
strobe mode illustrated like this:
(1) set HS_TIMIMG (Highspeed)
(2) Host change freq to <= 52Mhz
(3) set the bus width to Enhanced strobe and DDR8Bit(CMD6), EXT_CSD[183] = 0x86
instead of 0x80
(4) set HS_TIMING to 0x3 (HS400)
(5) Host change freq to <= 200Mhz
(6) Host select HS400 enhanced strobe complete

I can't find a upstreamed controller claimed to support it, as well as the
mmc stack. But my "arasan,sdhci-5.1" actually supports this function. So I decide
to work for this part.

By looking into the SDHCI spec, I find there isn't any registers to enable the
enhanced strobe function. But from my "arasan,sdhci-5.1" databook, it describes a
register called VENDOR_REGISTER(0x78) to trigger this mode. So I guess other sdhci
variant drivers may also need s vendor specific register to deal with it.

If we are sure that our controller supports enhanced strobe mode, just add
mmc-hs400-enhanced-strobe in DT. Once emmc devices claims to support this mode,
we enable it automatically. Of course, other sdhci*/non-sdhci drivers should
implement/overwrite the prepare_enhanced_strobe by themselves. I believe all of the
platforms which need to support this mode should do some basic preparation for their
controllers. Currently I just limit the callback within ths scope of arasan,sdhci-5.1,
but I prone to believe arasan will use VENDOR_REGISTER to tirgger this mode from now on
because I do believe vendor will consider the registers' compatibility.

With this patchset applied, we can successfully run in HS400 enhanced strobe mode on
RK3399 platform with Samsung eMMC KLMBG2JENB-B041(v5.1, 16GB).

mmc1: new HS400 Enhanced strobe MMC card at address 0001
mmcblk0: mmc1:0001 AJNB4R 14.6 GiB
mmcblk0boot0: mmc1:0001 AJNB4R partition 1 4.00 MiB
mmcblk0boot1: mmc1:0001 AJNB4R partition 2 4.00 MiB
mmcblk0rpmb: mmc1:0001 AJNB4R partition 3 4.00 MiB

Also I check this patchset with removing some caps to make sure
all the init sequences for hs400/hs200/DDR52/HighSpeed is correct.


Changes in v5:
- avoid to call hs400_enhanced+_strobe in mmc_set_initial_state
  if no setting MMC_CAP2_HS400_ES.
- add Adrian's ack for patch[5/5]

Changes in v4:
- check avail_type with EXT_CSD_CARD_TYPE_HS400 instead of
  card_type
- check if host support 8-bit when selecting hs400es
- some minor fix suggested by Douglas and add his review tag

Changes in v3:
- remove helper function and shorten cap2 to MMC_CAP2_HS400_ES
- rename callback to hs400_enhanced_strobe and make it return void
- add enhanced_strobe in mmc_ios and pass it to hs400_enhanced_strobe
- disable host's enhanced strobe in mmc_set_initial_state
- remove bus checking after switching hs400es
- add new function for hs400es timing selection
- fix wrong judgement of mmc_card_hs400es

Changes in v2:
- switch to HS400ES from Highspeed mode directly

Shawn Lin (5):
  Documentation: mmc: add mmc-hs400-enhanced-strobe
  mmc: core: add mmc-hs400-enhanced-strobe support
  mmc: core: implement enhanced strobe support
  mmc: debugfs: add HS400 enhanced strobe description
  mmc: sdhci-of-arasan: implement enhanced strobe callback

 Documentation/devicetree/bindings/mmc/mmc.txt |  1 +
 drivers/mmc/core/bus.c                        |  3 +-
 drivers/mmc/core/core.c                       |  9 +++
 drivers/mmc/core/debugfs.c                    |  4 +-
 drivers/mmc/core/host.c                       |  2 +
 drivers/mmc/core/mmc.c                        | 84 ++++++++++++++++++++++++++-
 drivers/mmc/host/sdhci-of-arasan.c            | 20 +++++++
 include/linux/mmc/card.h                      |  1 +
 include/linux/mmc/host.h                      | 12 ++++
 include/linux/mmc/mmc.h                       |  3 +
 10 files changed, 135 insertions(+), 4 deletions(-)

-- 
2.3.7

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#1405089 — [PATCH v5 2/5] mmc: core: add mmc-hs400-enhanced-strobe support

This patch introduce mmc-hs400-enhanced-strobe for platforms
which want to enable enhanced strobe function from DT if the
mmc host controller claims to support enhanced strobe.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>

---

Changes in v5:
- avoid to call hs400_enhanced+_strobe in mmc_set_initial_state
  if no setting MMC_CAP2_HS400_ES.
- add Adrian's ack for patch[5/5]

Changes in v4:
- check avail_type with EXT_CSD_CARD_TYPE_HS400 instead of
  card_type
- check if host support 8-bit when selecting hs400es
- some minor fix suggested by Douglas and add his review tag

Changes in v3:
- remove helper function and shorten cap2 to MMC_CAP2_HS400_ES
- rename callback to hs400_enhanced_strobe and make it return void
- add enhanced_strobe in mmc_ios and pass it to hs400_enhanced_strobe
- disable host's enhanced strobe in mmc_set_initial_state
- remove bus checking after switching hs400es
- add new function for hs400es timing selection
- fix wrong judgement of mmc_card_hs400es

Changes in v2:
- switch to HS400ES from Highspeed mode directly

 drivers/mmc/core/host.c  | 2 ++
 include/linux/mmc/host.h | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index e0a3ee1..45773e4 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -289,6 +289,8 @@ int mmc_of_parse(struct mmc_host *host)
 		host->caps2 |= MMC_CAP2_HS400_1_8V | MMC_CAP2_HS200_1_8V_SDR;
 	if (of_property_read_bool(np, "mmc-hs400-1_2v"))
 		host->caps2 |= MMC_CAP2_HS400_1_2V | MMC_CAP2_HS200_1_2V_SDR;
+	if (of_property_read_bool(np, "mmc-hs400-enhanced-strobe"))
+		host->caps2 |= MMC_CAP2_HS400_ES;
 
 	host->dsr_req = !of_property_read_u32(np, "dsr", &host->dsr);
 	if (host->dsr_req && (host->dsr & ~0xffff)) {
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 85800b4..2a06fb0 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -302,6 +302,7 @@ struct mmc_host {
 #define MMC_CAP2_SDIO_IRQ_NOTHREAD (1 << 17)
 #define MMC_CAP2_NO_WRITE_PROTECT (1 << 18)	/* No physical write protect pin, assume that card is always read-write */
 #define MMC_CAP2_NO_SDIO	(1 << 19)	/* Do not send SDIO commands during initialization */
+#define MMC_CAP2_HS400_ES	(1 << 20)	/* Host supports enhanced strobe */
 
 	mmc_pm_flag_t		pm_caps;	/* supported pm features */
 
-- 
2.3.7

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#1405624 — Re: [PATCH v5 2/5] mmc: core: add mmc-hs400-enhanced-strobe support

Shawn,

On Sun, May 22, 2016 at 9:13 PM, Shawn Lin <shawn.lin@rock-chips.com> wrote:
> This patch introduce mmc-hs400-enhanced-strobe for platforms
> which want to enable enhanced strobe function from DT if the
> mmc host controller claims to support enhanced strobe.
>
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
>
> ---
>
> Changes in v5:
> - avoid to call hs400_enhanced+_strobe in mmc_set_initial_state
>   if no setting MMC_CAP2_HS400_ES.
> - add Adrian's ack for patch[5/5]
>
> Changes in v4:
> - check avail_type with EXT_CSD_CARD_TYPE_HS400 instead of
>   card_type
> - check if host support 8-bit when selecting hs400es
> - some minor fix suggested by Douglas and add his review tag
>
> Changes in v3:
> - remove helper function and shorten cap2 to MMC_CAP2_HS400_ES
> - rename callback to hs400_enhanced_strobe and make it return void
> - add enhanced_strobe in mmc_ios and pass it to hs400_enhanced_strobe
> - disable host's enhanced strobe in mmc_set_initial_state
> - remove bus checking after switching hs400es
> - add new function for hs400es timing selection
> - fix wrong judgement of mmc_card_hs400es
>
> Changes in v2:
> - switch to HS400ES from Highspeed mode directly
>
>  drivers/mmc/core/host.c  | 2 ++
>  include/linux/mmc/host.h | 1 +
>  2 files changed, 3 insertions(+)

Reviewed-by: Douglas Anderson <dianders@chromium.org>

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#1406044 — Re: [PATCH v5 2/5] mmc: core: add mmc-hs400-enhanced-strobe support

On 05/23/2016 01:13 PM, Shawn Lin wrote:
> This patch introduce mmc-hs400-enhanced-strobe for platforms
> which want to enable enhanced strobe function from DT if the
> mmc host controller claims to support enhanced strobe.
> 
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>

Tested-by: Jaehoon Chung <jh80.chung@samsung.com>

Best Regards,
Jaehoon Chung

> 
> ---
> 
> Changes in v5:
> - avoid to call hs400_enhanced+_strobe in mmc_set_initial_state
>   if no setting MMC_CAP2_HS400_ES.
> - add Adrian's ack for patch[5/5]
> 
> Changes in v4:
> - check avail_type with EXT_CSD_CARD_TYPE_HS400 instead of
>   card_type
> - check if host support 8-bit when selecting hs400es
> - some minor fix suggested by Douglas and add his review tag
> 
> Changes in v3:
> - remove helper function and shorten cap2 to MMC_CAP2_HS400_ES
> - rename callback to hs400_enhanced_strobe and make it return void
> - add enhanced_strobe in mmc_ios and pass it to hs400_enhanced_strobe
> - disable host's enhanced strobe in mmc_set_initial_state
> - remove bus checking after switching hs400es
> - add new function for hs400es timing selection
> - fix wrong judgement of mmc_card_hs400es
> 
> Changes in v2:
> - switch to HS400ES from Highspeed mode directly
> 
>  drivers/mmc/core/host.c  | 2 ++
>  include/linux/mmc/host.h | 1 +
>  2 files changed, 3 insertions(+)
> 
> diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> index e0a3ee1..45773e4 100644
> --- a/drivers/mmc/core/host.c
> +++ b/drivers/mmc/core/host.c
> @@ -289,6 +289,8 @@ int mmc_of_parse(struct mmc_host *host)
>  		host->caps2 |= MMC_CAP2_HS400_1_8V | MMC_CAP2_HS200_1_8V_SDR;
>  	if (of_property_read_bool(np, "mmc-hs400-1_2v"))
>  		host->caps2 |= MMC_CAP2_HS400_1_2V | MMC_CAP2_HS200_1_2V_SDR;
> +	if (of_property_read_bool(np, "mmc-hs400-enhanced-strobe"))
> +		host->caps2 |= MMC_CAP2_HS400_ES;
>  
>  	host->dsr_req = !of_property_read_u32(np, "dsr", &host->dsr);
>  	if (host->dsr_req && (host->dsr & ~0xffff)) {
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 85800b4..2a06fb0 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -302,6 +302,7 @@ struct mmc_host {
>  #define MMC_CAP2_SDIO_IRQ_NOTHREAD (1 << 17)
>  #define MMC_CAP2_NO_WRITE_PROTECT (1 << 18)	/* No physical write protect pin, assume that card is always read-write */
>  #define MMC_CAP2_NO_SDIO	(1 << 19)	/* Do not send SDIO commands during initialization */
> +#define MMC_CAP2_HS400_ES	(1 << 20)	/* Host supports enhanced strobe */
>  
>  	mmc_pm_flag_t		pm_caps;	/* supported pm features */
>  
> 

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