2023-05-16 03:54:41

by Kiwoong Kim

Subject: [PATCH v2] ufs: poll HCS.UCRDY before issuing a UIC command

v1 -> v2: replace usleep_range with udelay
because it's a sleepable period.

With auto hibern8 enabled, UIC could be working
for a while to process a hibern8 operation and HCI
reports UIC not ready for a short term through HCS.UCRDY.
And UFS driver can't recognize the operation.
UFSHCI spec specifies UCRDY like this:
whether the host controller is ready to process UIC COMMAND

The 'ready' could be seen as many different meanings. If the meaning
includes not processing any request from HCI, processing a hibern8
operation can be 'not ready'. In this situation, the driver needs to
wait until the operations is completed.

Signed-off-by: Kiwoong Kim <[email protected]>
---
drivers/ufs/core/ufshcd.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 9434328..5f6819a 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -2365,7 +2365,18 @@ static inline int ufshcd_hba_capabilities(struct ufs_hba *hba)
*/
static inline bool ufshcd_ready_for_uic_cmd(struct ufs_hba *hba)
{
- return ufshcd_readl(hba, REG_CONTROLLER_STATUS) & UIC_COMMAND_READY;
+ ktime_t timeout = ktime_add_ms(ktime_get(), UIC_CMD_TIMEOUT);
+ u32 val = 0;
+
+ do {
+ val = ufshcd_readl(hba, REG_CONTROLLER_STATUS) &
+ UIC_COMMAND_READY;
+ if (val)
+ break;
+ udelay(500);
+ } while (ktime_before(ktime_get(), timeout));
+
+ return val ? true : false;
}

/**
--
2.7.4

2023-05-19 22:38:34

by Bart Van Assche

Subject: Re: [PATCH v2] ufs: poll HCS.UCRDY before issuing a UIC command

On 5/15/23 20:33, Kiwoong Kim wrote:
> v1 -> v2: replace usleep_range with udelay
> because it's a sleepable period.
>
> With auto hibern8 enabled, UIC could be working
> for a while to process a hibern8 operation and HCI
> reports UIC not ready for a short term through HCS.UCRDY.
> And UFS driver can't recognize the operation.
> UFSHCI spec specifies UCRDY like this:
> whether the host controller is ready to process UIC COMMAND
>
> The 'ready' could be seen as many different meanings. If the meaning
> includes not processing any request from HCI, processing a hibern8
> operation can be 'not ready'. In this situation, the driver needs to
> wait until the operations is completed.
>
> Signed-off-by: Kiwoong Kim <[email protected]>
> ---
> drivers/ufs/core/ufshcd.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 9434328..5f6819a 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -2365,7 +2365,18 @@ static inline int ufshcd_hba_capabilities(struct ufs_hba *hba)
> */
> static inline bool ufshcd_ready_for_uic_cmd(struct ufs_hba *hba)
> {
> - return ufshcd_readl(hba, REG_CONTROLLER_STATUS) & UIC_COMMAND_READY;
> + ktime_t timeout = ktime_add_ms(ktime_get(), UIC_CMD_TIMEOUT);
> + u32 val = 0;
> +
> + do {
> + val = ufshcd_readl(hba, REG_CONTROLLER_STATUS) &
> + UIC_COMMAND_READY;
> + if (val)
> + break;
> + udelay(500);
> + } while (ktime_before(ktime_get(), timeout));
> +
> + return val ? true : false;
> }

Sleeping during up to 500 ms while holding a spin lock is not acceptable.
Has it been considered to modify the UFS core such that the host_lock is
not held around calls of the above function, e.g. via the (untested) patch
below?

Thanks,

Bart.


diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 9736b2b4120e..394283b04d7c 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -2416,7 +2416,6 @@ __ufshcd_send_uic_cmd(struct ufs_hba *hba, struct uic_command *uic_cmd,
bool completion)
{
lockdep_assert_held(&hba->uic_cmd_mutex);
- lockdep_assert_held(hba->host->host_lock);

if (!ufshcd_ready_for_uic_cmd(hba)) {
dev_err(hba->dev,
@@ -2452,9 +2451,7 @@ int ufshcd_send_uic_cmd(struct ufs_hba *hba, struct uic_command *uic_cmd)
mutex_lock(&hba->uic_cmd_mutex);
ufshcd_add_delay_before_dme_cmd(hba);

- spin_lock_irqsave(hba->host->host_lock, flags);
ret = __ufshcd_send_uic_cmd(hba, uic_cmd, true);
- spin_unlock_irqrestore(hba->host->host_lock, flags);
if (!ret)
ret = ufshcd_wait_for_uic_cmd(hba, uic_cmd);

@@ -4122,8 +4119,8 @@ static int ufshcd_uic_pwr_ctrl(struct ufs_hba *hba, struct uic_command *cmd)
wmb();
reenable_intr = true;
}
- ret = __ufshcd_send_uic_cmd(hba, cmd, false);
spin_unlock_irqrestore(hba->host->host_lock, flags);
+ ret = __ufshcd_send_uic_cmd(hba, cmd, false);
if (ret) {
dev_err(hba->dev,
"pwr ctrl cmd 0x%x with mode 0x%x uic error %d\n",