* [PATCH] platform: x86: intel_scu_ipc: Replace mdelay with usleep_range in intel_scu_ipc_i2c_cntrl
@ 2018-04-10 12:57 Jia-Ju Bai
2018-04-10 15:25 ` Andy Shevchenko
0 siblings, 1 reply; 2+ messages in thread
From: Jia-Ju Bai @ 2018-04-10 12:57 UTC (permalink / raw)
To: dvhart, andy; +Cc: platform-driver-x86, linux-kernel, Jia-Ju Bai
intel_scu_ipc_i2c_cntrl() calls mutex_lock(), which indicates
this function is not called in atomic context.
Despite never getting called from atomic context,
intel_scu_ipc_i2c_cntrl() calls mdelay to busily wait.
This is not necessary and can be replaced with usleep_range to
avoid busy waiting.
This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
drivers/platform/x86/intel_scu_ipc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/platform/x86/intel_scu_ipc.c b/drivers/platform/x86/intel_scu_ipc.c
index 2c85f75..75c8fef 100644
--- a/drivers/platform/x86/intel_scu_ipc.c
+++ b/drivers/platform/x86/intel_scu_ipc.c
@@ -584,11 +584,11 @@ int intel_scu_ipc_i2c_cntrl(u32 addr, u32 *data)
if (cmd == IPC_I2C_READ) {
writel(addr, scu->i2c_base + IPC_I2C_CNTRL_ADDR);
/* Write not getting updated without delay */
- mdelay(1);
+ usleep_range(1000, 2000);
*data = readl(scu->i2c_base + I2C_DATA_ADDR);
} else if (cmd == IPC_I2C_WRITE) {
writel(*data, scu->i2c_base + I2C_DATA_ADDR);
- mdelay(1);
+ usleep_range(1000, 2000);
writel(addr, scu->i2c_base + IPC_I2C_CNTRL_ADDR);
} else {
dev_err(scu->dev,
--
1.9.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] platform: x86: intel_scu_ipc: Replace mdelay with usleep_range in intel_scu_ipc_i2c_cntrl
2018-04-10 12:57 [PATCH] platform: x86: intel_scu_ipc: Replace mdelay with usleep_range in intel_scu_ipc_i2c_cntrl Jia-Ju Bai
@ 2018-04-10 15:25 ` Andy Shevchenko
0 siblings, 0 replies; 2+ messages in thread
From: Andy Shevchenko @ 2018-04-10 15:25 UTC (permalink / raw)
To: Jia-Ju Bai
Cc: Darren Hart, Andy Shevchenko, Platform Driver, Linux Kernel Mailing List
On Tue, Apr 10, 2018 at 3:57 PM, Jia-Ju Bai <baijiaju1990@gmail.com> wrote:
> intel_scu_ipc_i2c_cntrl() calls mutex_lock(), which indicates
> this function is not called in atomic context.
>
> Despite never getting called from atomic context,
> intel_scu_ipc_i2c_cntrl() calls mdelay to busily wait.
> This is not necessary and can be replaced with usleep_range to
> avoid busy waiting.
>
> This is found by a static analysis tool named DCNS written by myself.
> And I also manually check it.
I'm not sure we even need that delay at all.
Anyway, pushed to my review and testing queue, thanks!
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
> ---
> drivers/platform/x86/intel_scu_ipc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/platform/x86/intel_scu_ipc.c b/drivers/platform/x86/intel_scu_ipc.c
> index 2c85f75..75c8fef 100644
> --- a/drivers/platform/x86/intel_scu_ipc.c
> +++ b/drivers/platform/x86/intel_scu_ipc.c
> @@ -584,11 +584,11 @@ int intel_scu_ipc_i2c_cntrl(u32 addr, u32 *data)
> if (cmd == IPC_I2C_READ) {
> writel(addr, scu->i2c_base + IPC_I2C_CNTRL_ADDR);
> /* Write not getting updated without delay */
> - mdelay(1);
> + usleep_range(1000, 2000);
> *data = readl(scu->i2c_base + I2C_DATA_ADDR);
> } else if (cmd == IPC_I2C_WRITE) {
> writel(*data, scu->i2c_base + I2C_DATA_ADDR);
> - mdelay(1);
> + usleep_range(1000, 2000);
> writel(addr, scu->i2c_base + IPC_I2C_CNTRL_ADDR);
> } else {
> dev_err(scu->dev,
> --
> 1.9.1
>
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2018-04-10 15:25 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-04-10 12:57 [PATCH] platform: x86: intel_scu_ipc: Replace mdelay with usleep_range in intel_scu_ipc_i2c_cntrl Jia-Ju Bai
2018-04-10 15:25 ` Andy Shevchenko
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).