[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,

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