On 12/15/2016 04:11 PM, Phil Reid wrote:
On 15/12/2016 20:33, Andy Shevchenko wrote:
On Thu, 2016-12-15 at 16:59 +0800, Zhangfei Gao wrote:
Some platforms like hi3660 need do reset first to allow accessing
registers
Patch itself looks good, but would be nice to have it tested.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
---
drivers/i2c/busses/i2c-designware-core.h | 1 +
drivers/i2c/busses/i2c-designware-platdrv.c | 28
++++++++++++++++++++++++----
2 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/drivers/i2c/busses/i2c-designware-core.h
b/drivers/i2c/busses/i2c-designware-core.h
index 0d44d2a..94b14fa 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -80,6 +80,7 @@ struct dw_i2c_dev {
void __iomem *base;
struct completion cmd_complete;
struct clk *clk;
+ struct reset_control *rst;
u32 (*get_clk_rate_khz) (struct
dw_i2c_dev *dev);
struct dw_pci_controller *controller;
int cmd_err;
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c
b/drivers/i2c/busses/i2c-designware-platdrv.c
index 0b42a12..e9016ae 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -38,6 +38,7 @@
#include <linux/pm_runtime.h>
#include <linux/property.h>
#include <linux/io.h>
+#include <linux/reset.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/platform_data/i2c-designware.h>
@@ -176,6 +177,14 @@ static int dw_i2c_plat_probe(struct
platform_device *pdev)
dev->irq = irq;
platform_set_drvdata(pdev, dev);
+ dev->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
+ if (IS_ERR(dev->rst)) {
+ if (PTR_ERR(dev->rst) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
+ } else {
+ reset_control_deassert(dev->rst);
+ }
+
More for my education. But some drivers seem to handle the error codes a
little more explicitly.
Whats the best approach?
eg: From usb/dwc2 driver it continues only if ENOENT / ENOTSUPP errors
are return
and ENOMEM / EINVAL etc is a fatal error.
hsotg->reset = devm_reset_control_get_optional(hsotg->dev, "dwc2");
if (IS_ERR(hsotg->reset)) {
ret = PTR_ERR(hsotg->reset);
switch (ret) {
case -ENOENT:
case -ENOTSUPP:
hsotg->reset = NULL;
break;
default:
dev_err(hsotg->dev, "error getting reset control %d\n",
ret);
return ret;
}
This looks a bit extreme. At least we shouldn't spam log on machines
that don't need reset control. I kind of think it's good enough to do
like the patch does. I.e. handle only EPROBE_DEFER and let all other
errors fall through and keep the controller in reset and let the
dev->rst carry an error code.
I guess EINVAL is likely seen by developer only. ENOMEM is so fatal that
things are already falling apart somewhere else too and I don't think it
needs special handling here.
--
Jarkko
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