Some eMMCs disable their hardware reset line (RST_N) by default. To enable
it the host must set the corresponding bit in ECSD. An example for such
a device is the Micron MTFCxGACAANA-4M.
This patch adds a new mmc-card devicetree property to let the host enable
this feature during card initialization.
Signed-off-by: Richard Leitner <[email protected]>
---
Documentation/devicetree/bindings/mmc/mmc-card.txt | 3 +++
drivers/mmc/core/mmc.c | 21 +++++++++++++++++++++
2 files changed, 24 insertions(+)
diff --git a/Documentation/devicetree/bindings/mmc/mmc-card.txt b/Documentation/devicetree/bindings/mmc/mmc-card.txt
index a70fcd6..8590a40 100644
--- a/Documentation/devicetree/bindings/mmc/mmc-card.txt
+++ b/Documentation/devicetree/bindings/mmc/mmc-card.txt
@@ -12,6 +12,9 @@ Required properties:
Optional properties:
-broken-hpi : Use this to indicate that the mmc-card has a broken hpi
implementation, and that hpi should not be used
+-enable-hw-reset : some eMMC devices have disabled the hw reset functionality
+ (RST_N_FUNCTION) by default. By adding this property the
+ host will enable it during initialization.
Example:
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index b502601..518d0e3 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1520,9 +1520,16 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
int err;
u32 cid[4];
u32 rocr;
+ struct device_node *np;
+ bool enable_rst_n = false;
WARN_ON(!host->claimed);
+ np = mmc_of_find_child_device(host, 0);
+ if (np && of_device_is_compatible(np, "mmc-card"))
+ enable_rst_n = of_property_read_bool(np, "enable-hw-reset");
+ of_node_put(np);
+
/* Set correct bus mode for MMC before attempting init */
if (!mmc_host_is_spi(host))
mmc_set_bus_mode(host, MMC_BUSMODE_OPENDRAIN);
@@ -1810,6 +1817,20 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
}
}
+ /*
+ * try to enable RST_N if requested
+ * This is needed because some eMMC chips disable this function by
+ * default.
+ */
+ if (enable_rst_n) {
+ err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+ EXT_CSD_RST_N_FUNCTION, EXT_CSD_RST_N_ENABLED,
+ card->ext_csd.generic_cmd6_time);
+ if (err && err != -EBADMSG)
+ pr_warn("%s: Enabling RST_N feature failed\n",
+ mmc_hostname(card->host));
+ }
+
if (!oldcard)
host->card = card;
--
2.1.4
Hi,
On 04/04/2017 11:16 PM, Richard Leitner wrote:
> Some eMMCs disable their hardware reset line (RST_N) by default. To enable
> it the host must set the corresponding bit in ECSD. An example for such
> a device is the Micron MTFCxGACAANA-4M.
>
> This patch adds a new mmc-card devicetree property to let the host enable
> this feature during card initialization.
>
> Signed-off-by: Richard Leitner <[email protected]>
> ---
> Documentation/devicetree/bindings/mmc/mmc-card.txt | 3 +++
> drivers/mmc/core/mmc.c | 21 +++++++++++++++++++++
> 2 files changed, 24 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mmc/mmc-card.txt b/Documentation/devicetree/bindings/mmc/mmc-card.txt
> index a70fcd6..8590a40 100644
> --- a/Documentation/devicetree/bindings/mmc/mmc-card.txt
> +++ b/Documentation/devicetree/bindings/mmc/mmc-card.txt
> @@ -12,6 +12,9 @@ Required properties:
> Optional properties:
> -broken-hpi : Use this to indicate that the mmc-card has a broken hpi
> implementation, and that hpi should not be used
> +-enable-hw-reset : some eMMC devices have disabled the hw reset functionality
> + (RST_N_FUNCTION) by default. By adding this property the
> + host will enable it during initialization.
As i know, RST_N_FUNCTION is controlled bit[1:0]
0x0 : RST_n disabled (by default)
0x1 : permanently enabled
0x2 : permanently disabled
I think that it needs to add the description about these..
>
> Example:
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index b502601..518d0e3 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1520,9 +1520,16 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
> int err;
> u32 cid[4];
> u32 rocr;
> + struct device_node *np;
> + bool enable_rst_n = false;
>
> WARN_ON(!host->claimed);
>
> + np = mmc_of_find_child_device(host, 0);
> + if (np && of_device_is_compatible(np, "mmc-card"))
> + enable_rst_n = of_property_read_bool(np, "enable-hw-reset");
> + of_node_put(np);
> +
> /* Set correct bus mode for MMC before attempting init */
> if (!mmc_host_is_spi(host))
> mmc_set_bus_mode(host, MMC_BUSMODE_OPENDRAIN);
> @@ -1810,6 +1817,20 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
> }
> }
>
> + /*
> + * try to enable RST_N if requested
> + * This is needed because some eMMC chips disable this function by
> + * default.
> + */
> + if (enable_rst_n) {
> + err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> + EXT_CSD_RST_N_FUNCTION, EXT_CSD_RST_N_ENABLED,
> + card->ext_csd.generic_cmd6_time);
> + if (err && err != -EBADMSG)
> + pr_warn("%s: Enabling RST_N feature failed\n",
> + mmc_hostname(card->host));
> + }
If enabled hw-reset, it doesn't need to re-enable this bit.
i didn't check the mmc-util..
If mmc-util provides the changing this, the using mmc-util is better than this.
Best Regards,
Jaehoon Chung
> +
> if (!oldcard)
> host->card = card;
>
>
On 04/05/2017 06:40 AM, Jaehoon Chung wrote:
> Hi,
>
> On 04/04/2017 11:16 PM, Richard Leitner wrote:
>> Some eMMCs disable their hardware reset line (RST_N) by default. To enable
>> it the host must set the corresponding bit in ECSD. An example for such
>> a device is the Micron MTFCxGACAANA-4M.
>>
>> This patch adds a new mmc-card devicetree property to let the host enable
>> this feature during card initialization.
>>
>> Signed-off-by: Richard Leitner <[email protected]>
>> ---
>> Documentation/devicetree/bindings/mmc/mmc-card.txt | 3 +++
>> drivers/mmc/core/mmc.c | 21 +++++++++++++++++++++
>> 2 files changed, 24 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/mmc/mmc-card.txt b/Documentation/devicetree/bindings/mmc/mmc-card.txt
>> index a70fcd6..8590a40 100644
>> --- a/Documentation/devicetree/bindings/mmc/mmc-card.txt
>> +++ b/Documentation/devicetree/bindings/mmc/mmc-card.txt
>> @@ -12,6 +12,9 @@ Required properties:
>> Optional properties:
>> -broken-hpi : Use this to indicate that the mmc-card has a broken hpi
>> implementation, and that hpi should not be used
>> +-enable-hw-reset : some eMMC devices have disabled the hw reset functionality
>> + (RST_N_FUNCTION) by default. By adding this property the
>> + host will enable it during initialization.
>
> As i know, RST_N_FUNCTION is controlled bit[1:0]
> 0x0 : RST_n disabled (by default)
> 0x1 : permanently enabled
> 0x2 : permanently disabled
>
> I think that it needs to add the description about these..
Ok.
>>
>> Example:
>>
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index b502601..518d0e3 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -1520,9 +1520,16 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
>> int err;
>> u32 cid[4];
>> u32 rocr;
>> + struct device_node *np;
>> + bool enable_rst_n = false;
>>
>> WARN_ON(!host->claimed);
>>
>> + np = mmc_of_find_child_device(host, 0);
>> + if (np && of_device_is_compatible(np, "mmc-card"))
>> + enable_rst_n = of_property_read_bool(np, "enable-hw-reset");
>> + of_node_put(np);
>> +
>> /* Set correct bus mode for MMC before attempting init */
>> if (!mmc_host_is_spi(host))
>> mmc_set_bus_mode(host, MMC_BUSMODE_OPENDRAIN);
>> @@ -1810,6 +1817,20 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
>> }
>> }
>>
>> + /*
>> + * try to enable RST_N if requested
>> + * This is needed because some eMMC chips disable this function by
>> + * default.
>> + */
>> + if (enable_rst_n) {
>> + err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> + EXT_CSD_RST_N_FUNCTION, EXT_CSD_RST_N_ENABLED,
>> + card->ext_csd.generic_cmd6_time);
>> + if (err && err != -EBADMSG)
>> + pr_warn("%s: Enabling RST_N feature failed\n",
>> + mmc_hostname(card->host));
>> + }
>
> If enabled hw-reset, it doesn't need to re-enable this bit.
Ok. I can add a check to prevent setting it, if it is set already.
> i didn't check the mmc-util..
> If mmc-util provides the changing this, the using mmc-util is better than this.
mmc-utils is providing a enable/disable hwreset feature. But as this
setting is required for my hardware to allow rebooting it, I thought it
would be better if it's in the kernel. So I/the hw doesn't have to
depend on userspace tools.
Nonetheless you're the experts, therefore if you say it shouldn't be in
the kernel/dt I'd be fine with that too. ;-)
On Wed, Apr 05, 2017 at 08:23:29AM +0200, Richard Leitner wrote:
> On 04/05/2017 06:40 AM, Jaehoon Chung wrote:
> > Hi,
> >
> > On 04/04/2017 11:16 PM, Richard Leitner wrote:
> >> Some eMMCs disable their hardware reset line (RST_N) by default. To enable
> >> it the host must set the corresponding bit in ECSD. An example for such
> >> a device is the Micron MTFCxGACAANA-4M.
> >>
> >> This patch adds a new mmc-card devicetree property to let the host enable
> >> this feature during card initialization.
> >>
> >> Signed-off-by: Richard Leitner <[email protected]>
> >> ---
> >> Documentation/devicetree/bindings/mmc/mmc-card.txt | 3 +++
> >> drivers/mmc/core/mmc.c | 21 +++++++++++++++++++++
> >> 2 files changed, 24 insertions(+)
> >>
> >> diff --git a/Documentation/devicetree/bindings/mmc/mmc-card.txt b/Documentation/devicetree/bindings/mmc/mmc-card.txt
> >> index a70fcd6..8590a40 100644
> >> --- a/Documentation/devicetree/bindings/mmc/mmc-card.txt
> >> +++ b/Documentation/devicetree/bindings/mmc/mmc-card.txt
> >> @@ -12,6 +12,9 @@ Required properties:
> >> Optional properties:
> >> -broken-hpi : Use this to indicate that the mmc-card has a broken hpi
> >> implementation, and that hpi should not be used
> >> +-enable-hw-reset : some eMMC devices have disabled the hw reset functionality
> >> + (RST_N_FUNCTION) by default. By adding this property the
> >> + host will enable it during initialization.
> >
> > As i know, RST_N_FUNCTION is controlled bit[1:0]
> > 0x0 : RST_n disabled (by default)
> > 0x1 : permanently enabled
> > 0x2 : permanently disabled
> >
> > I think that it needs to add the description about these..
>
> Ok.
>
> >>
> >> Example:
> >>
> >> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> >> index b502601..518d0e3 100644
> >> --- a/drivers/mmc/core/mmc.c
> >> +++ b/drivers/mmc/core/mmc.c
> >> @@ -1520,9 +1520,16 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
> >> int err;
> >> u32 cid[4];
> >> u32 rocr;
> >> + struct device_node *np;
> >> + bool enable_rst_n = false;
> >>
> >> WARN_ON(!host->claimed);
> >>
> >> + np = mmc_of_find_child_device(host, 0);
> >> + if (np && of_device_is_compatible(np, "mmc-card"))
> >> + enable_rst_n = of_property_read_bool(np, "enable-hw-reset");
> >> + of_node_put(np);
> >> +
> >> /* Set correct bus mode for MMC before attempting init */
> >> if (!mmc_host_is_spi(host))
> >> mmc_set_bus_mode(host, MMC_BUSMODE_OPENDRAIN);
> >> @@ -1810,6 +1817,20 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
> >> }
> >> }
> >>
> >> + /*
> >> + * try to enable RST_N if requested
> >> + * This is needed because some eMMC chips disable this function by
> >> + * default.
> >> + */
> >> + if (enable_rst_n) {
> >> + err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> >> + EXT_CSD_RST_N_FUNCTION, EXT_CSD_RST_N_ENABLED,
> >> + card->ext_csd.generic_cmd6_time);
> >> + if (err && err != -EBADMSG)
> >> + pr_warn("%s: Enabling RST_N feature failed\n",
> >> + mmc_hostname(card->host));
> >> + }
> >
> > If enabled hw-reset, it doesn't need to re-enable this bit.
>
> Ok. I can add a check to prevent setting it, if it is set already.
>
> > i didn't check the mmc-util..
> > If mmc-util provides the changing this, the using mmc-util is better than this.
>
> mmc-utils is providing a enable/disable hwreset feature. But as this
> setting is required for my hardware to allow rebooting it, I thought it
> would be better if it's in the kernel. So I/the hw doesn't have to
> depend on userspace tools.
Doesn't really seem like something you'd want a user to have to care
about, so in DT seems fine to me.
Rob