On Thu, Nov 21, 2019 at 10:10:51AM +0100, Jean Delvare wrote:
> From: Corey Minyard <cminyard@xxxxxxxxxx>
>
> Getting the same alert twice in a row is legal and normal,
> especially on a fast device (like running in qemu). Kind of
> like interrupts. So don't report duplicate alerts, and deliver
> them normally.
>
> [JD: Fixed subject]
>
> Signed-off-by: Corey Minyard <cminyard@xxxxxxxxxx>
> Signed-off-by: Jean Delvare <jdelvare@xxxxxxx>
> ---
> That's a 4-year-old patch from Corey which I stumbled upon this
> morning. I was supposed to test it on my ADM1032 evaluation board but
> never got to it. Sorry about that. It turns out that I no longer have
> any system with a parallel port to test it.
Thanks. This hasn't been a huge deal, since the only system that is
affected at the moment (AFAIK) is the qemu test environment that I use.
But it will be nice to have this for when something real actually uses
this.
-corey
>
> I think the patch is correct and whatever the problem was on my ADM1032
> evaluation board, it should be fixed differently. Maybe it was a wrong
> trigger type, or alerts must be disabled temporarily during processing,
> or the hardware is actually bogus and it would be up to the device
> driver to ignore alerts for some time after receiving one. Whatever,
> let's apply the fix now and deal with this problem later if/when it
> resurfaces.
>
> drivers/i2c/i2c-smbus.c | 7 -------
> 1 file changed, 7 deletions(-)
>
> diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
> index 94765a8..cecd423 100644
> --- a/drivers/i2c/i2c-smbus.c
> +++ b/drivers/i2c/i2c-smbus.c
> @@ -75,7 +75,6 @@ static void smbus_alert(struct work_struct *work)
> {
> struct i2c_smbus_alert *alert;
> struct i2c_client *ara;
> - unsigned short prev_addr = 0; /* Not a valid address */
>
> alert = container_of(work, struct i2c_smbus_alert, alert);
> ara = alert->ara;
> @@ -99,18 +98,12 @@ static void smbus_alert(struct work_struct *work)
> data.flag = status & 1;
> data.addr = status >> 1;
>
> - if (data.addr == prev_addr) {
> - dev_warn(&ara->dev, "Duplicate SMBALERT# from dev "
> - "0x%02x, skipping\n", data.addr);
> - break;
> - }
> dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
> data.addr, data.flag);
>
> /* Notify driver for the device which issued the alert */
> device_for_each_child(&ara->adapter->dev, &data,
> smbus_do_alert);
> - prev_addr = data.addr;
> }
>
> /* We handled all alerts; re-enable level-triggered IRQs */
>
>
> --
> Jean Delvare
> SUSE L3 Support
