[i2c-next,v3,2/3] i2c: aspeed: Add 'aspeed, timeout' DT property reading code

Message ID 20180926215842.23125-3-jae.hyun.yoo@linux.intel.com
State New
Headers show
Series
  • i2c: aspeed: Add bus idle waiting logic for multi-master use cases
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Commit Message

Jae Hyun Yoo Sept. 26, 2018, 9:58 p.m.
This commit adds reading code of the 'aspeed,timeout' DT property
to set 'timeout' value in adapter configuration. This value still
case be configured through an I2C_TIMEOUT ioctl on cdev too.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
---
 drivers/i2c/busses/i2c-aspeed.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

Comments

Joel Stanley Sept. 27, 2018, 3:11 a.m. | #1
On Thu, 27 Sep 2018 at 01:58, Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com> wrote:
>
> This commit adds reading code of the 'aspeed,timeout' DT property
> to set 'timeout' value in adapter configuration. This value still
> case be configured through an I2C_TIMEOUT ioctl on cdev too.
>
> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
> ---
>  drivers/i2c/busses/i2c-aspeed.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
> index 8dc9161ced38..0d934ce0c028 100644
> --- a/drivers/i2c/busses/i2c-aspeed.c
> +++ b/drivers/i2c/busses/i2c-aspeed.c
> @@ -115,6 +115,9 @@
>  /* 0x18 : I2CD Slave Device Address Register   */
>  #define ASPEED_I2CD_DEV_ADDR_MASK                      GENMASK(6, 0)
>
> +/* Timeout */
> +#define ASPEED_I2C_BUS_TIMEOUT_US_DEFAULT              (5 * 1000 * 1000)

The 5 seconds time out is way too long. On a system that doesn't have
functional i2c, this holds up boot for a long time as most i2c client
drivers try to initialise their device and fail. I realise you're not
changing the value, but we should pick a better default. 1 second?
Half a second?

> +
>  enum aspeed_i2c_master_state {
>         ASPEED_I2C_MASTER_INACTIVE,
>         ASPEED_I2C_MASTER_START,
> @@ -885,6 +888,7 @@ static int aspeed_i2c_probe_bus(struct platform_device *pdev)
>         struct clk *parent_clk;
>         struct resource *res;
>         int irq, ret;
> +       u32 timeout_us;
>
>         bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
>         if (!bus)
> @@ -918,6 +922,11 @@ static int aspeed_i2c_probe_bus(struct platform_device *pdev)
>                 bus->bus_frequency = 100000;
>         }
>
> +       ret = of_property_read_u32(pdev->dev.of_node, "aspeed,timeout",
> +                                  &timeout_us);

Can we make this binding generic? It's not specific to aspeed's
hardware. Getting the value could even part of the i2c core.

I read the previous thread with Wolfram. I think this would still fit
with what Wolfram suggested, but please forgive my jetlagged brain if
I've missed something.

Cheers,

Joel
> +       if (ret)
> +               timeout_us = ASPEED_I2C_BUS_TIMEOUT_US_DEFAULT;
> +
>         match = of_match_node(aspeed_i2c_bus_of_table, pdev->dev.of_node);
>         if (!match)
>                 bus->get_clk_reg_val = aspeed_i2c_24xx_get_clk_reg_val;
> @@ -930,7 +939,7 @@ static int aspeed_i2c_probe_bus(struct platform_device *pdev)
>         init_completion(&bus->cmd_complete);
>         bus->adap.owner = THIS_MODULE;
>         bus->adap.retries = 0;
> -       bus->adap.timeout = 5 * HZ;
> +       bus->adap.timeout = usecs_to_jiffies(timeout_us);
>         bus->adap.algo = &aspeed_i2c_algo;
>         bus->adap.dev.parent = &pdev->dev;
>         bus->adap.dev.of_node = pdev->dev.of_node;
> --
> 2.19.0
>
Jae Hyun Yoo Sept. 27, 2018, 5:41 p.m. | #2
Hi Joel,

On 9/26/2018 8:11 PM, Joel Stanley wrote:
> On Thu, 27 Sep 2018 at 01:58, Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com> wrote:
>>
>> +/* Timeout */
>> +#define ASPEED_I2C_BUS_TIMEOUT_US_DEFAULT              (5 * 1000 * 1000)
> 
> The 5 seconds time out is way too long. On a system that doesn't have
> functional i2c, this holds up boot for a long time as most i2c client
> drivers try to initialise their device and fail. I realise you're not
> changing the value, but we should pick a better default. 1 second?
> Half a second?
> 

I agree with you. We could probably use 1 second as default which can
cover the most of general cases. If so, we don't need to make the
default setting in this driver because i2c-core-base will default
adap->timeout to 1 second if the value is 0 when a driver registers an
adapter. Will fix this code.

>>
>> +       ret = of_property_read_u32(pdev->dev.of_node, "aspeed,timeout",
>> +                                  &timeout_us);
> 
> Can we make this binding generic? It's not specific to aspeed's
> hardware. Getting the value could even part of the i2c core.
> 
> I read the previous thread with Wolfram. I think this would still fit
> with what Wolfram suggested, but please forgive my jetlagged brain if
> I've missed something.
> 

It followed the way of the existing i2c-mpc driver uses 'fsl,timeout'
for the same purpose. Though, I also want to make it as a generic as you
suggested like 'timeout' in milliseconds unit, not in microseconds unit.
If making it a generic property is acceptable, I'll fix it too.

Wolfram, can you please share your thought on it?

Thanks,
Jae

Patch

diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
index 8dc9161ced38..0d934ce0c028 100644
--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c
@@ -115,6 +115,9 @@ 
 /* 0x18 : I2CD Slave Device Address Register   */
 #define ASPEED_I2CD_DEV_ADDR_MASK			GENMASK(6, 0)
 
+/* Timeout */
+#define ASPEED_I2C_BUS_TIMEOUT_US_DEFAULT		(5 * 1000 * 1000)
+
 enum aspeed_i2c_master_state {
 	ASPEED_I2C_MASTER_INACTIVE,
 	ASPEED_I2C_MASTER_START,
@@ -885,6 +888,7 @@  static int aspeed_i2c_probe_bus(struct platform_device *pdev)
 	struct clk *parent_clk;
 	struct resource *res;
 	int irq, ret;
+	u32 timeout_us;
 
 	bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
 	if (!bus)
@@ -918,6 +922,11 @@  static int aspeed_i2c_probe_bus(struct platform_device *pdev)
 		bus->bus_frequency = 100000;
 	}
 
+	ret = of_property_read_u32(pdev->dev.of_node, "aspeed,timeout",
+				   &timeout_us);
+	if (ret)
+		timeout_us = ASPEED_I2C_BUS_TIMEOUT_US_DEFAULT;
+
 	match = of_match_node(aspeed_i2c_bus_of_table, pdev->dev.of_node);
 	if (!match)
 		bus->get_clk_reg_val = aspeed_i2c_24xx_get_clk_reg_val;
@@ -930,7 +939,7 @@  static int aspeed_i2c_probe_bus(struct platform_device *pdev)
 	init_completion(&bus->cmd_complete);
 	bus->adap.owner = THIS_MODULE;
 	bus->adap.retries = 0;
-	bus->adap.timeout = 5 * HZ;
+	bus->adap.timeout = usecs_to_jiffies(timeout_us);
 	bus->adap.algo = &aspeed_i2c_algo;
 	bus->adap.dev.parent = &pdev->dev;
 	bus->adap.dev.of_node = pdev->dev.of_node;