[PATCH] nvme: check for readiness more quickly to speed up boot

[PATCH] nvme: check for readiness more quickly to speed up boot

[Christian Berry via B4 Relay]

From: Christian Berry <christiankbberry@gmail.com>

nvme_wait_ready() polls the controller status every 100ms, although
the controller may become ready much sooner. Every probe then waits
at least 100ms longer than needed, and possibly twice, since both
nvme_disable_ctrl() and nvme_enable_ctrl() wait for readiness.

Poll every millisecond instead, as Linux does since commit
3e98c2443f5c ("nvme: Check for readiness more quickly, to speed up
boot time"). The overall timeout is still based on elapsed time, so
it is unaffected.

Tested on an Arm64 SoC with a Samsung 980 SSD in a Gen3 x4
configuration, where PCIe + NVMe probe time dropped from 165 ms to
65 ms.

Signed-off-by: Christian Berry <christiankbberry@gmail.com>
---
 drivers/nvme/host/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 345707ecfe..9686268d44 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -173,7 +173,7 @@ static int nvme_wait_ready(struct nvme_ctrl *ctrl, u64 cap, bool enabled)
 		if ((csts & NVME_CSTS_RDY) == bit)
 			break;
 
-		mdelay(100);
+		udelay(1000);
 
 		if (is_timeout(start, timeout)) {
 			dev_err(ctrl->dev,

---
base-commit: 983608b439b803f72f12d56d0ab10bd6ba29e536
change-id: 20260927-nvme-ready-poll-4bd640377bab

Best regards,
-- 
Christian Berry <christiankbberry@gmail.com>

Re: [PATCH] nvme: check for readiness more quickly to speed up boot

[Ahmad Fatoum]

On 9/28/26 1:03 AM, Christian Berry via B4 Relay wrote:
> From: Christian Berry <christiankbberry@gmail.com>
> 
> nvme_wait_ready() polls the controller status every 100ms, although
> the controller may become ready much sooner. Every probe then waits
> at least 100ms longer than needed, and possibly twice, since both
> nvme_disable_ctrl() and nvme_enable_ctrl() wait for readiness.
> 
> Poll every millisecond instead, as Linux does since commit
> 3e98c2443f5c ("nvme: Check for readiness more quickly, to speed up
> boot time"). The overall timeout is still based on elapsed time, so
> it is unaffected.
> 
> Tested on an Arm64 SoC with a Samsung 980 SSD in a Gen3 x4
> configuration, where PCIe + NVMe probe time dropped from 165 ms to
> 65 ms.
> 
> Signed-off-by: Christian Berry <christiankbberry@gmail.com>

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

> ---
>  drivers/nvme/host/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 345707ecfe..9686268d44 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -173,7 +173,7 @@ static int nvme_wait_ready(struct nvme_ctrl *ctrl, u64 cap, bool enabled)
>  		if ((csts & NVME_CSTS_RDY) == bit)
>  			break;
>  
> -		mdelay(100);
> +		udelay(1000);

Nitpick: I'd prefer mdelay(1); but you don't need to resend just for this.

Cheers,
Ahmad

>  
>  		if (is_timeout(start, timeout)) {
>  			dev_err(ctrl->dev,
> 
> ---
> base-commit: 983608b439b803f72f12d56d0ab10bd6ba29e536
> change-id: 20260927-nvme-ready-poll-4bd640377bab
> 
> Best regards,

-- 
Pengutronix e.K.                  |                             |
Steuerwalder Str. 21              | http://www.pengutronix.de/  |
31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |

Re: [PATCH] nvme: check for readiness more quickly to speed up boot

[Christian Berry]

  On 9/28/26 10:19, Ahmad Fatoum wrote:
  > Nitpick: I'd prefer mdelay(1); but you don't need to resend just for this.

  Thanks for the response,

  I went with udelay(1000) intentionally, to mirror Linux's
  usleep_range(1000, 2000) in the equivalent NVMe readiness poll
  (commit 3e98c2443f5c). mdelay(1) would work too, and I did consider
  it over udelay(1000) but keeping the barebox and Linux implementations
  easy to compare side by side seemed worth it. Happy to switch if you
  feel strongly; otherwise, I'll leave it as-is per your note.

  Thanks again,
  Christian


On Mon, Sep 28, 2026 at 4:18 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote:
>
> On 9/28/26 1:03 AM, Christian Berry via B4 Relay wrote:
> > From: Christian Berry <christiankbberry@gmail.com>
> >
> > nvme_wait_ready() polls the controller status every 100ms, although
> > the controller may become ready much sooner. Every probe then waits
> > at least 100ms longer than needed, and possibly twice, since both
> > nvme_disable_ctrl() and nvme_enable_ctrl() wait for readiness.
> >
> > Poll every millisecond instead, as Linux does since commit
> > 3e98c2443f5c ("nvme: Check for readiness more quickly, to speed up
> > boot time"). The overall timeout is still based on elapsed time, so
> > it is unaffected.
> >
> > Tested on an Arm64 SoC with a Samsung 980 SSD in a Gen3 x4
> > configuration, where PCIe + NVMe probe time dropped from 165 ms to
> > 65 ms.
> >
> > Signed-off-by: Christian Berry <christiankbberry@gmail.com>
>
> Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
>
> > ---
> >  drivers/nvme/host/core.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> > index 345707ecfe..9686268d44 100644
> > --- a/drivers/nvme/host/core.c
> > +++ b/drivers/nvme/host/core.c
> > @@ -173,7 +173,7 @@ static int nvme_wait_ready(struct nvme_ctrl *ctrl, u64 cap, bool enabled)
> >               if ((csts & NVME_CSTS_RDY) == bit)
> >                       break;
> >
> > -             mdelay(100);
> > +             udelay(1000);
>
> Nitpick: I'd prefer mdelay(1); but you don't need to resend just for this.
>
> Cheers,
> Ahmad
>
> >
> >               if (is_timeout(start, timeout)) {
> >                       dev_err(ctrl->dev,
> >
> > ---
> > base-commit: 983608b439b803f72f12d56d0ab10bd6ba29e536
> > change-id: 20260927-nvme-ready-poll-4bd640377bab
> >
> > Best regards,
>
> --
> Pengutronix e.K.                  |                             |
> Steuerwalder Str. 21              | http://www.pengutronix.de/  |
> 31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |
>

Re: [PATCH] nvme: check for readiness more quickly to speed up boot

[Ahmad Fatoum]

Hi,

On 9/28/26 2:08 PM, Christian Berry wrote:
>   On 9/28/26 10:19, Ahmad Fatoum wrote:
>   > Nitpick: I'd prefer mdelay(1); but you don't need to resend just for this.
> 
>   Thanks for the response,
> 
>   I went with udelay(1000) intentionally, to mirror Linux's
>   usleep_range(1000, 2000) in the equivalent NVMe readiness poll
>   (commit 3e98c2443f5c). mdelay(1) would work too, and I did consider
>   it over udelay(1000) but keeping the barebox and Linux implementations
>   easy to compare side by side seemed worth it. Happy to switch if you
>   feel strongly; otherwise, I'll leave it as-is per your note.

Fair enough. Thanks for the elaboration!

Cheers,
Ahmad

> 
>   Thanks again,
>   Christian
> 
> 
> On Mon, Sep 28, 2026 at 4:18 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote:
>>
>> On 9/28/26 1:03 AM, Christian Berry via B4 Relay wrote:
>>> From: Christian Berry <christiankbberry@gmail.com>
>>>
>>> nvme_wait_ready() polls the controller status every 100ms, although
>>> the controller may become ready much sooner. Every probe then waits
>>> at least 100ms longer than needed, and possibly twice, since both
>>> nvme_disable_ctrl() and nvme_enable_ctrl() wait for readiness.
>>>
>>> Poll every millisecond instead, as Linux does since commit
>>> 3e98c2443f5c ("nvme: Check for readiness more quickly, to speed up
>>> boot time"). The overall timeout is still based on elapsed time, so
>>> it is unaffected.
>>>
>>> Tested on an Arm64 SoC with a Samsung 980 SSD in a Gen3 x4
>>> configuration, where PCIe + NVMe probe time dropped from 165 ms to
>>> 65 ms.
>>>
>>> Signed-off-by: Christian Berry <christiankbberry@gmail.com>
>>
>> Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
>>
>>> ---
>>>  drivers/nvme/host/core.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>>> index 345707ecfe..9686268d44 100644
>>> --- a/drivers/nvme/host/core.c
>>> +++ b/drivers/nvme/host/core.c
>>> @@ -173,7 +173,7 @@ static int nvme_wait_ready(struct nvme_ctrl *ctrl, u64 cap, bool enabled)
>>>               if ((csts & NVME_CSTS_RDY) == bit)
>>>                       break;
>>>
>>> -             mdelay(100);
>>> +             udelay(1000);
>>
>> Nitpick: I'd prefer mdelay(1); but you don't need to resend just for this.
>>
>> Cheers,
>> Ahmad
>>
>>>
>>>               if (is_timeout(start, timeout)) {
>>>                       dev_err(ctrl->dev,
>>>
>>> ---
>>> base-commit: 983608b439b803f72f12d56d0ab10bd6ba29e536
>>> change-id: 20260927-nvme-ready-poll-4bd640377bab
>>>
>>> Best regards,
>>
>> --
>> Pengutronix e.K.                  |                             |
>> Steuerwalder Str. 21              | http://www.pengutronix.de/  |
>> 31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
>> Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |
>>

-- 
Pengutronix e.K.                  |                             |
Steuerwalder Str. 21              | http://www.pengutronix.de/  |
31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |