* [PATCH] mmc: sdhci: Disable SD card clock before changing parameters
@ 2025-02-11 21:46 Erick Shepherd
2025-03-06 8:12 ` Adrian Hunter
` (2 more replies)
0 siblings, 3 replies; 12+ messages in thread
From: Erick Shepherd @ 2025-02-11 21:46 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mmc, ulf.hansson, adrian.hunter, gratian.crisan,
Erick Shepherd, Kyle Roeschley, Brad Mouring
Per the SD Host Controller Simplified Specification v4.20 §3.2.3, change
the SD card clock parameters only after first disabling the external card
clock. Doing this fixes a spurious clock pulse on Baytrail and Apollo Lake
SD controllers which otherwise breaks voltage switching with a specific
Swissbit SD card.
Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
Signed-off-by: Brad Mouring <brad.mouring@ni.com>
Signed-off-by: Erick Shepherd <erick.shepherd@ni.com>
---
drivers/mmc/host/sdhci.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index f4a7733a8ad2..5f91b44891f9 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2065,10 +2065,15 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
host->mmc->actual_clock = 0;
- sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
+ clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+ if (clk & SDHCI_CLOCK_CARD_EN)
+ sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN,
+ SDHCI_CLOCK_CONTROL);
- if (clock == 0)
+ if (clock == 0) {
+ sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
return;
+ }
clk = sdhci_calc_clk(host, clock, &host->mmc->actual_clock);
sdhci_enable_clk(host, clk);
--
2.43.0
^ permalink raw reply related [flat|nested] 12+ messages in thread* Re: [PATCH] mmc: sdhci: Disable SD card clock before changing parameters
2025-02-11 21:46 [PATCH] mmc: sdhci: Disable SD card clock before changing parameters Erick Shepherd
@ 2025-03-06 8:12 ` Adrian Hunter
2025-03-12 11:24 ` Ulf Hansson
2025-06-19 3:29 ` Jonathan Liu
2 siblings, 0 replies; 12+ messages in thread
From: Adrian Hunter @ 2025-03-06 8:12 UTC (permalink / raw)
To: Erick Shepherd, linux-kernel
Cc: linux-mmc, ulf.hansson, gratian.crisan, Kyle Roeschley,
Brad Mouring
On 11/02/25 23:46, Erick Shepherd wrote:
> Per the SD Host Controller Simplified Specification v4.20 §3.2.3, change
> the SD card clock parameters only after first disabling the external card
> clock. Doing this fixes a spurious clock pulse on Baytrail and Apollo Lake
> SD controllers which otherwise breaks voltage switching with a specific
> Swissbit SD card.
>
> Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
> Signed-off-by: Brad Mouring <brad.mouring@ni.com>
> Signed-off-by: Erick Shepherd <erick.shepherd@ni.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
> drivers/mmc/host/sdhci.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index f4a7733a8ad2..5f91b44891f9 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2065,10 +2065,15 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
>
> host->mmc->actual_clock = 0;
>
> - sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
> + clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> + if (clk & SDHCI_CLOCK_CARD_EN)
> + sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN,
> + SDHCI_CLOCK_CONTROL);
>
> - if (clock == 0)
> + if (clock == 0) {
> + sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
> return;
> + }
>
> clk = sdhci_calc_clk(host, clock, &host->mmc->actual_clock);
> sdhci_enable_clk(host, clk);
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH] mmc: sdhci: Disable SD card clock before changing parameters
2025-02-11 21:46 [PATCH] mmc: sdhci: Disable SD card clock before changing parameters Erick Shepherd
2025-03-06 8:12 ` Adrian Hunter
@ 2025-03-12 11:24 ` Ulf Hansson
2025-06-19 3:29 ` Jonathan Liu
2 siblings, 0 replies; 12+ messages in thread
From: Ulf Hansson @ 2025-03-12 11:24 UTC (permalink / raw)
To: Erick Shepherd
Cc: linux-kernel, linux-mmc, adrian.hunter, gratian.crisan,
Kyle Roeschley, Brad Mouring
On Tue, 11 Feb 2025 at 22:47, Erick Shepherd <erick.shepherd@ni.com> wrote:
>
> Per the SD Host Controller Simplified Specification v4.20 §3.2.3, change
> the SD card clock parameters only after first disabling the external card
> clock. Doing this fixes a spurious clock pulse on Baytrail and Apollo Lake
> SD controllers which otherwise breaks voltage switching with a specific
> Swissbit SD card.
>
> Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
> Signed-off-by: Brad Mouring <brad.mouring@ni.com>
> Signed-off-by: Erick Shepherd <erick.shepherd@ni.com>
Applied for next, thanks!
Kind regards
Uffe
> ---
> drivers/mmc/host/sdhci.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index f4a7733a8ad2..5f91b44891f9 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2065,10 +2065,15 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
>
> host->mmc->actual_clock = 0;
>
> - sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
> + clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> + if (clk & SDHCI_CLOCK_CARD_EN)
> + sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN,
> + SDHCI_CLOCK_CONTROL);
>
> - if (clock == 0)
> + if (clock == 0) {
> + sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
> return;
> + }
>
> clk = sdhci_calc_clk(host, clock, &host->mmc->actual_clock);
> sdhci_enable_clk(host, clk);
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH] mmc: sdhci: Disable SD card clock before changing parameters
2025-02-11 21:46 [PATCH] mmc: sdhci: Disable SD card clock before changing parameters Erick Shepherd
2025-03-06 8:12 ` Adrian Hunter
2025-03-12 11:24 ` Ulf Hansson
@ 2025-06-19 3:29 ` Jonathan Liu
2025-06-24 10:53 ` Adrian Hunter
2 siblings, 1 reply; 12+ messages in thread
From: Jonathan Liu @ 2025-06-19 3:29 UTC (permalink / raw)
To: Erick Shepherd
Cc: linux-kernel, linux-mmc, ulf.hansson, adrian.hunter,
gratian.crisan, Kyle Roeschley, Brad Mouring
Hi Erick,
On Tue, 11 Feb 2025 at 15:46, Erick Shepherd <erick.shepherd@ni.com> wrote:
>
> Per the SD Host Controller Simplified Specification v4.20 §3.2.3, change
> the SD card clock parameters only after first disabling the external card
> clock. Doing this fixes a spurious clock pulse on Baytrail and Apollo Lake
> SD controllers which otherwise breaks voltage switching with a specific
> Swissbit SD card.
>
> Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
> Signed-off-by: Brad Mouring <brad.mouring@ni.com>
> Signed-off-by: Erick Shepherd <erick.shepherd@ni.com>
> ---
> drivers/mmc/host/sdhci.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index f4a7733a8ad2..5f91b44891f9 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2065,10 +2065,15 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
>
> host->mmc->actual_clock = 0;
>
> - sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
> + clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> + if (clk & SDHCI_CLOCK_CARD_EN)
> + sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN,
> + SDHCI_CLOCK_CONTROL);
>
> - if (clock == 0)
> + if (clock == 0) {
> + sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
> return;
> + }
>
> clk = sdhci_calc_clk(host, clock, &host->mmc->actual_clock);
> sdhci_enable_clk(host, clk);
> --
> 2.43.0
This commit is causing eMMC to sometimes fail to detect on my RK3399
ARM64 board after updating from v5.10.237 to v5.10.238.
Any ideas?
Regards,
Jonathan
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH] mmc: sdhci: Disable SD card clock before changing parameters
2025-06-19 3:29 ` Jonathan Liu
@ 2025-06-24 10:53 ` Adrian Hunter
2025-07-22 21:29 ` Erick Shepherd
0 siblings, 1 reply; 12+ messages in thread
From: Adrian Hunter @ 2025-06-24 10:53 UTC (permalink / raw)
To: Erick Shepherd
Cc: linux-kernel, linux-mmc, ulf.hansson, gratian.crisan,
Kyle Roeschley, Brad Mouring, Jonathan Liu
On 19/06/2025 06:29, Jonathan Liu wrote:
> Hi Erick,
>
> On Tue, 11 Feb 2025 at 15:46, Erick Shepherd <erick.shepherd@ni.com> wrote:
>>
>> Per the SD Host Controller Simplified Specification v4.20 §3.2.3, change
>> the SD card clock parameters only after first disabling the external card
>> clock. Doing this fixes a spurious clock pulse on Baytrail and Apollo Lake
>> SD controllers which otherwise breaks voltage switching with a specific
>> Swissbit SD card.
>>
>> Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
>> Signed-off-by: Brad Mouring <brad.mouring@ni.com>
>> Signed-off-by: Erick Shepherd <erick.shepherd@ni.com>
>> ---
>> drivers/mmc/host/sdhci.c | 9 +++++++--
>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index f4a7733a8ad2..5f91b44891f9 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -2065,10 +2065,15 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
>>
>> host->mmc->actual_clock = 0;
>>
>> - sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
>> + clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
>> + if (clk & SDHCI_CLOCK_CARD_EN)
>> + sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN,
>> + SDHCI_CLOCK_CONTROL);
>>
>> - if (clock == 0)
>> + if (clock == 0) {
>> + sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
>> return;
>> + }
>>
>> clk = sdhci_calc_clk(host, clock, &host->mmc->actual_clock);
>> sdhci_enable_clk(host, clk);
>> --
>> 2.43.0
>
> This commit is causing eMMC to sometimes fail to detect on my RK3399
> ARM64 board after updating from v5.10.237 to v5.10.238.
> Any ideas?
Looks like this patch will get reverted.
After that, would something like the following work instead?
diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
index dd084c8750f9..ad95218fe3b3 100644
--- a/drivers/mmc/host/sdhci-pci-core.c
+++ b/drivers/mmc/host/sdhci-pci-core.c
@@ -679,8 +679,19 @@ static int intel_start_signal_voltage_switch(struct mmc_host *mmc,
return 0;
}
+static void sdhci_intel_set_clock(struct sdhci_host *host, unsigned int clock)
+{
+ u16 clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+
+ /* Stop card clock separately to avoid glitches on clock line */
+ if (clk & SDHCI_CLOCK_CARD_EN)
+ sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN, SDHCI_CLOCK_CONTROL);
+
+ sdhci_set_clock(host, clock);
+}
+
static const struct sdhci_ops sdhci_intel_byt_ops = {
- .set_clock = sdhci_set_clock,
+ .set_clock = sdhci_intel_set_clock,
.set_power = sdhci_intel_set_power,
.enable_dma = sdhci_pci_enable_dma,
.set_bus_width = sdhci_set_bus_width,
@@ -690,7 +701,7 @@ static const struct sdhci_ops sdhci_intel_byt_ops = {
};
static const struct sdhci_ops sdhci_intel_glk_ops = {
- .set_clock = sdhci_set_clock,
+ .set_clock = sdhci_intel_set_clock,
.set_power = sdhci_intel_set_power,
.enable_dma = sdhci_pci_enable_dma,
.set_bus_width = sdhci_set_bus_width,
^ permalink raw reply related [flat|nested] 12+ messages in thread* Re: [PATCH] mmc: sdhci: Disable SD card clock before changing parameters
2025-06-24 10:53 ` Adrian Hunter
@ 2025-07-22 21:29 ` Erick Shepherd
2025-07-23 6:09 ` Adrian Hunter
0 siblings, 1 reply; 12+ messages in thread
From: Erick Shepherd @ 2025-07-22 21:29 UTC (permalink / raw)
To: adrian.hunter
Cc: brad.mouring, erick.shepherd, gratian.crisan, kyle.roeschley,
linux-kernel, linux-mmc, net147, ulf.hansson
Hi Adrian,
I believe this fix would work since it looks like it keeps the
functionality of the previous change but only for intel SD
controllers. I also tested your proposed change on one of our devices
with a Baytrail SD controller and a Swissbit SD card and did not run
into any issues.
Regards,
Erick
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] mmc: sdhci: Disable SD card clock before changing parameters
2025-07-22 21:29 ` Erick Shepherd
@ 2025-07-23 6:09 ` Adrian Hunter
0 siblings, 0 replies; 12+ messages in thread
From: Adrian Hunter @ 2025-07-23 6:09 UTC (permalink / raw)
To: Erick Shepherd
Cc: brad.mouring, gratian.crisan, kyle.roeschley, linux-kernel,
linux-mmc, net147, ulf.hansson
On 23/07/2025 00:29, Erick Shepherd wrote:
> Hi Adrian,
>
> I believe this fix would work since it looks like it keeps the
> functionality of the previous change but only for intel SD
> controllers. I also tested your proposed change on one of our devices
> with a Baytrail SD controller and a Swissbit SD card and did not run
> into any issues.
If you are OK with it, please submit it as a patch
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH] mmc: sdhci: Disable SD card clock before changing parameters
@ 2025-07-23 21:42 Erick Shepherd
2025-07-24 10:54 ` Adrian Hunter
0 siblings, 1 reply; 12+ messages in thread
From: Erick Shepherd @ 2025-07-23 21:42 UTC (permalink / raw)
To: linux-mmc
Cc: ulf.hansson, adrian.hunter, Erick Shepherd, Kyle Roeschley,
Brad Mouring
Per the SD Host Controller Simplified Specification v4.20 §3.2.3, change
the SD card clock parameters only after first disabling the external card
clock. Doing this fixes a spurious clock pulse on Baytrail and Apollo Lake
SD controllers which otherwise breaks voltage switching with a specific
Swissbit SD card. This change is limited to Intel host controllers to
avoid an issue reported on ARM64 devices.
Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
Signed-off-by: Brad Mouring <brad.mouring@ni.com>
Signed-off-by: Erick Shepherd <erick.shepherd@ni.com>
---
drivers/mmc/host/sdhci-pci-core.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
index b0b1d403f352..d586dbaecae5 100644
--- a/drivers/mmc/host/sdhci-pci-core.c
+++ b/drivers/mmc/host/sdhci-pci-core.c
@@ -689,8 +689,19 @@ static int intel_start_signal_voltage_switch(struct mmc_host *mmc,
return 0;
}
+static void sdhci_intel_set_clock(struct sdhci_host *host, unsigned int clock)
+{
+ u16 clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+
+ /* Stop card clock separately to avoid glitches on clock line */
+ if (clk & SDHCI_CLOCK_CARD_EN)
+ sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN, SDHCI_CLOCK_CONTROL);
+
+ sdhci_set_clock(host, clock);
+}
+
static const struct sdhci_ops sdhci_intel_byt_ops = {
- .set_clock = sdhci_set_clock,
+ .set_clock = sdhci_intel_set_clock,
.set_power = sdhci_intel_set_power,
.enable_dma = sdhci_pci_enable_dma,
.set_bus_width = sdhci_set_bus_width,
@@ -700,7 +711,7 @@ static const struct sdhci_ops sdhci_intel_byt_ops = {
};
static const struct sdhci_ops sdhci_intel_glk_ops = {
- .set_clock = sdhci_set_clock,
+ .set_clock = sdhci_intel_set_clock,
.set_power = sdhci_intel_set_power,
.enable_dma = sdhci_pci_enable_dma,
.set_bus_width = sdhci_set_bus_width,
--
2.43.0
^ permalink raw reply related [flat|nested] 12+ messages in thread* Re: [PATCH] mmc: sdhci: Disable SD card clock before changing parameters
2025-07-23 21:42 Erick Shepherd
@ 2025-07-24 10:54 ` Adrian Hunter
2025-07-24 18:53 ` Erick Shepherd
0 siblings, 1 reply; 12+ messages in thread
From: Adrian Hunter @ 2025-07-24 10:54 UTC (permalink / raw)
To: Erick Shepherd, linux-mmc; +Cc: ulf.hansson, Kyle Roeschley, Brad Mouring
On 24/07/2025 00:42, Erick Shepherd wrote:
> Per the SD Host Controller Simplified Specification v4.20 §3.2.3, change
> the SD card clock parameters only after first disabling the external card
> clock. Doing this fixes a spurious clock pulse on Baytrail and Apollo Lake
> SD controllers which otherwise breaks voltage switching with a specific
> Swissbit SD card. This change is limited to Intel host controllers to
> avoid an issue reported on ARM64 devices.
>
> Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
> Signed-off-by: Brad Mouring <brad.mouring@ni.com>
> Signed-off-by: Erick Shepherd <erick.shepherd@ni.com>
One formatting error below, otherwise:
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
> drivers/mmc/host/sdhci-pci-core.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
> index b0b1d403f352..d586dbaecae5 100644
> --- a/drivers/mmc/host/sdhci-pci-core.c
> +++ b/drivers/mmc/host/sdhci-pci-core.c
> @@ -689,8 +689,19 @@ static int intel_start_signal_voltage_switch(struct mmc_host *mmc,
> return 0;
> }
>
> +static void sdhci_intel_set_clock(struct sdhci_host *host, unsigned int clock)
> +{
> + u16 clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +
> + /* Stop card clock separately to avoid glitches on clock line */
> + if (clk & SDHCI_CLOCK_CARD_EN)
> + sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN, SDHCI_CLOCK_CONTROL);
> +
> + sdhci_set_clock(host, clock);
The indent is a space but needs to be tab
> +}
> +
> static const struct sdhci_ops sdhci_intel_byt_ops = {
> - .set_clock = sdhci_set_clock,
> + .set_clock = sdhci_intel_set_clock,
> .set_power = sdhci_intel_set_power,
> .enable_dma = sdhci_pci_enable_dma,
> .set_bus_width = sdhci_set_bus_width,
> @@ -700,7 +711,7 @@ static const struct sdhci_ops sdhci_intel_byt_ops = {
> };
>
> static const struct sdhci_ops sdhci_intel_glk_ops = {
> - .set_clock = sdhci_set_clock,
> + .set_clock = sdhci_intel_set_clock,
> .set_power = sdhci_intel_set_power,
> .enable_dma = sdhci_pci_enable_dma,
> .set_bus_width = sdhci_set_bus_width,
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH] mmc: sdhci: Disable SD card clock before changing parameters
2025-07-24 10:54 ` Adrian Hunter
@ 2025-07-24 18:53 ` Erick Shepherd
2025-07-25 8:53 ` Adrian Hunter
2025-08-18 10:54 ` Ulf Hansson
0 siblings, 2 replies; 12+ messages in thread
From: Erick Shepherd @ 2025-07-24 18:53 UTC (permalink / raw)
To: adrian.hunter
Cc: brad.mouring, erick.shepherd, kyle.roeschley, linux-mmc,
ulf.hansson
Per the SD Host Controller Simplified Specification v4.20 §3.2.3, change
the SD card clock parameters only after first disabling the external card
clock. Doing this fixes a spurious clock pulse on Baytrail and Apollo Lake
SD controllers which otherwise breaks voltage switching with a specific
Swissbit SD card. This change is limited to Intel host controllers to
avoid an issue reported on ARM64 devices.
Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
Signed-off-by: Brad Mouring <brad.mouring@ni.com>
Signed-off-by: Erick Shepherd <erick.shepherd@ni.com>
---
drivers/mmc/host/sdhci-pci-core.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
index b0b1d403f352..7ef821d16d39 100644
--- a/drivers/mmc/host/sdhci-pci-core.c
+++ b/drivers/mmc/host/sdhci-pci-core.c
@@ -689,8 +689,19 @@ static int intel_start_signal_voltage_switch(struct mmc_host *mmc,
return 0;
}
+static void sdhci_intel_set_clock(struct sdhci_host *host, unsigned int clock)
+{
+ u16 clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+
+ /* Stop card clock separately to avoid glitches on clock line */
+ if (clk & SDHCI_CLOCK_CARD_EN)
+ sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN, SDHCI_CLOCK_CONTROL);
+
+ sdhci_set_clock(host, clock);
+}
+
static const struct sdhci_ops sdhci_intel_byt_ops = {
- .set_clock = sdhci_set_clock,
+ .set_clock = sdhci_intel_set_clock,
.set_power = sdhci_intel_set_power,
.enable_dma = sdhci_pci_enable_dma,
.set_bus_width = sdhci_set_bus_width,
@@ -700,7 +711,7 @@ static const struct sdhci_ops sdhci_intel_byt_ops = {
};
static const struct sdhci_ops sdhci_intel_glk_ops = {
- .set_clock = sdhci_set_clock,
+ .set_clock = sdhci_intel_set_clock,
.set_power = sdhci_intel_set_power,
.enable_dma = sdhci_pci_enable_dma,
.set_bus_width = sdhci_set_bus_width,
--
2.43.0
^ permalink raw reply related [flat|nested] 12+ messages in thread* Re: [PATCH] mmc: sdhci: Disable SD card clock before changing parameters
2025-07-24 18:53 ` Erick Shepherd
@ 2025-07-25 8:53 ` Adrian Hunter
2025-08-18 10:54 ` Ulf Hansson
1 sibling, 0 replies; 12+ messages in thread
From: Adrian Hunter @ 2025-07-25 8:53 UTC (permalink / raw)
To: Erick Shepherd; +Cc: brad.mouring, kyle.roeschley, linux-mmc, ulf.hansson
On 24/07/2025 21:53, Erick Shepherd wrote:
> Per the SD Host Controller Simplified Specification v4.20 §3.2.3, change
> the SD card clock parameters only after first disabling the external card
> clock. Doing this fixes a spurious clock pulse on Baytrail and Apollo Lake
> SD controllers which otherwise breaks voltage switching with a specific
> Swissbit SD card. This change is limited to Intel host controllers to
> avoid an issue reported on ARM64 devices.
>
> Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
> Signed-off-by: Brad Mouring <brad.mouring@ni.com>
> Signed-off-by: Erick Shepherd <erick.shepherd@ni.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
> drivers/mmc/host/sdhci-pci-core.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
> index b0b1d403f352..7ef821d16d39 100644
> --- a/drivers/mmc/host/sdhci-pci-core.c
> +++ b/drivers/mmc/host/sdhci-pci-core.c
> @@ -689,8 +689,19 @@ static int intel_start_signal_voltage_switch(struct mmc_host *mmc,
> return 0;
> }
>
> +static void sdhci_intel_set_clock(struct sdhci_host *host, unsigned int clock)
> +{
> + u16 clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +
> + /* Stop card clock separately to avoid glitches on clock line */
> + if (clk & SDHCI_CLOCK_CARD_EN)
> + sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN, SDHCI_CLOCK_CONTROL);
> +
> + sdhci_set_clock(host, clock);
> +}
> +
> static const struct sdhci_ops sdhci_intel_byt_ops = {
> - .set_clock = sdhci_set_clock,
> + .set_clock = sdhci_intel_set_clock,
> .set_power = sdhci_intel_set_power,
> .enable_dma = sdhci_pci_enable_dma,
> .set_bus_width = sdhci_set_bus_width,
> @@ -700,7 +711,7 @@ static const struct sdhci_ops sdhci_intel_byt_ops = {
> };
>
> static const struct sdhci_ops sdhci_intel_glk_ops = {
> - .set_clock = sdhci_set_clock,
> + .set_clock = sdhci_intel_set_clock,
> .set_power = sdhci_intel_set_power,
> .enable_dma = sdhci_pci_enable_dma,
> .set_bus_width = sdhci_set_bus_width,
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH] mmc: sdhci: Disable SD card clock before changing parameters
2025-07-24 18:53 ` Erick Shepherd
2025-07-25 8:53 ` Adrian Hunter
@ 2025-08-18 10:54 ` Ulf Hansson
1 sibling, 0 replies; 12+ messages in thread
From: Ulf Hansson @ 2025-08-18 10:54 UTC (permalink / raw)
To: Erick Shepherd; +Cc: adrian.hunter, brad.mouring, kyle.roeschley, linux-mmc
On Thu, 24 Jul 2025 at 20:54, Erick Shepherd <erick.shepherd@ni.com> wrote:
>
> Per the SD Host Controller Simplified Specification v4.20 §3.2.3, change
> the SD card clock parameters only after first disabling the external card
> clock. Doing this fixes a spurious clock pulse on Baytrail and Apollo Lake
> SD controllers which otherwise breaks voltage switching with a specific
> Swissbit SD card. This change is limited to Intel host controllers to
> avoid an issue reported on ARM64 devices.
>
> Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
> Signed-off-by: Brad Mouring <brad.mouring@ni.com>
> Signed-off-by: Erick Shepherd <erick.shepherd@ni.com>
Applied for next, thanks!
Kind regards
Uffe
> ---
> drivers/mmc/host/sdhci-pci-core.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
> index b0b1d403f352..7ef821d16d39 100644
> --- a/drivers/mmc/host/sdhci-pci-core.c
> +++ b/drivers/mmc/host/sdhci-pci-core.c
> @@ -689,8 +689,19 @@ static int intel_start_signal_voltage_switch(struct mmc_host *mmc,
> return 0;
> }
>
> +static void sdhci_intel_set_clock(struct sdhci_host *host, unsigned int clock)
> +{
> + u16 clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +
> + /* Stop card clock separately to avoid glitches on clock line */
> + if (clk & SDHCI_CLOCK_CARD_EN)
> + sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN, SDHCI_CLOCK_CONTROL);
> +
> + sdhci_set_clock(host, clock);
> +}
> +
> static const struct sdhci_ops sdhci_intel_byt_ops = {
> - .set_clock = sdhci_set_clock,
> + .set_clock = sdhci_intel_set_clock,
> .set_power = sdhci_intel_set_power,
> .enable_dma = sdhci_pci_enable_dma,
> .set_bus_width = sdhci_set_bus_width,
> @@ -700,7 +711,7 @@ static const struct sdhci_ops sdhci_intel_byt_ops = {
> };
>
> static const struct sdhci_ops sdhci_intel_glk_ops = {
> - .set_clock = sdhci_set_clock,
> + .set_clock = sdhci_intel_set_clock,
> .set_power = sdhci_intel_set_power,
> .enable_dma = sdhci_pci_enable_dma,
> .set_bus_width = sdhci_set_bus_width,
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2025-08-18 10:55 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-02-11 21:46 [PATCH] mmc: sdhci: Disable SD card clock before changing parameters Erick Shepherd
2025-03-06 8:12 ` Adrian Hunter
2025-03-12 11:24 ` Ulf Hansson
2025-06-19 3:29 ` Jonathan Liu
2025-06-24 10:53 ` Adrian Hunter
2025-07-22 21:29 ` Erick Shepherd
2025-07-23 6:09 ` Adrian Hunter
-- strict thread matches above, loose matches on Subject: below --
2025-07-23 21:42 Erick Shepherd
2025-07-24 10:54 ` Adrian Hunter
2025-07-24 18:53 ` Erick Shepherd
2025-07-25 8:53 ` Adrian Hunter
2025-08-18 10:54 ` Ulf Hansson
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