2018-05-03 11:15:14

by Asutosh Das (asd)

Subject: [PATCH v2 05/10] scsi: ufshcd: fix possible unclocked register access

From: Subhash Jadavani <[email protected]>

vendor specific setup_clocks ops may depend on clocks managed by ufshcd
driver so if the vendor specific setup_clocks callback is called when
the required clocks are turned off, it results into unclocked register
access.

This change make sure that required clocks are enabled before vendor
specific setup_clocks callback is called.

Signed-off-by: Subhash Jadavani <[email protected]>
Signed-off-by: Venkat Gopalakrishnan <[email protected]>
Signed-off-by: Can Guo <[email protected]>
Signed-off-by: Asutosh Das <[email protected]>
---
drivers/scsi/ufs/ufshcd.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 838ba8f0..dfeb194 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6780,9 +6780,16 @@ static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on,
if (list_empty(head))
goto out;

- ret = ufshcd_vops_setup_clocks(hba, on, PRE_CHANGE);
- if (ret)
- return ret;
+ /*
+ * vendor specific setup_clocks ops may depend on clocks managed by
+ * this standard driver hence call the vendor specific setup_clocks
+ * before disabling the clocks managed here.
+ */
+ if (!on) {
+ ret = ufshcd_vops_setup_clocks(hba, on, PRE_CHANGE);
+ if (ret)
+ return ret;
+ }

list_for_each_entry(clki, head, list) {
if (!IS_ERR_OR_NULL(clki->clk)) {
@@ -6806,9 +6813,16 @@ static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on,
}
}

- ret = ufshcd_vops_setup_clocks(hba, on, POST_CHANGE);
- if (ret)
- return ret;
+ /*
+ * vendor specific setup_clocks ops may depend on clocks managed by
+ * this standard driver hence call the vendor specific setup_clocks
+ * after enabling the clocks managed here.
+ */
+ if (on) {
+ ret = ufshcd_vops_setup_clocks(hba, on, POST_CHANGE);
+ if (ret)
+ return ret;
+ }

out:
if (ret) {
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

2018-05-16 21:14:12

by Subhash Jadavani

Subject: Re: [PATCH v2 05/10] scsi: ufshcd: fix possible unclocked register access

On 2018-05-03 04:07, Asutosh Das wrote:
> From: Subhash Jadavani <[email protected]>
>
> vendor specific setup_clocks ops may depend on clocks managed by ufshcd
> driver so if the vendor specific setup_clocks callback is called when
> the required clocks are turned off, it results into unclocked register
> access.
>
> This change make sure that required clocks are enabled before vendor
> specific setup_clocks callback is called.
>
> Signed-off-by: Subhash Jadavani <[email protected]>
> Signed-off-by: Venkat Gopalakrishnan <[email protected]>
> Signed-off-by: Can Guo <[email protected]>
> Signed-off-by: Asutosh Das <[email protected]>
> ---
> drivers/scsi/ufs/ufshcd.c | 26 ++++++++++++++++++++------
> 1 file changed, 20 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 838ba8f0..dfeb194 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -6780,9 +6780,16 @@ static int __ufshcd_setup_clocks(struct ufs_hba
> *hba, bool on,
> if (list_empty(head))
> goto out;
>
> - ret = ufshcd_vops_setup_clocks(hba, on, PRE_CHANGE);
> - if (ret)
> - return ret;
> + /*
> + * vendor specific setup_clocks ops may depend on clocks managed by
> + * this standard driver hence call the vendor specific setup_clocks
> + * before disabling the clocks managed here.
> + */
> + if (!on) {
> + ret = ufshcd_vops_setup_clocks(hba, on, PRE_CHANGE);
> + if (ret)
> + return ret;
> + }
>
> list_for_each_entry(clki, head, list) {
> if (!IS_ERR_OR_NULL(clki->clk)) {
> @@ -6806,9 +6813,16 @@ static int __ufshcd_setup_clocks(struct ufs_hba
> *hba, bool on,
> }
> }
>
> - ret = ufshcd_vops_setup_clocks(hba, on, POST_CHANGE);
> - if (ret)
> - return ret;
> + /*
> + * vendor specific setup_clocks ops may depend on clocks managed by
> + * this standard driver hence call the vendor specific setup_clocks
> + * after enabling the clocks managed here.
> + */
> + if (on) {
> + ret = ufshcd_vops_setup_clocks(hba, on, POST_CHANGE);
> + if (ret)
> + return ret;
> + }
>
> out:
> if (ret) {

Looks good to me.

--
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project