Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Mon, 17 Aug 2020 08:35:33 -0700
From:   Guenter Roeck <linux@roeck-us.net>
To:     Marius Zachmann <mail@mariuszachmann.de>
Cc:     Jean Delvare <jdelvare@suse.com>, linux-hwmon@vger.kernel.org,
        linux-kernel@vger.kernel.org, Jiri Kosina <jikos@kernel.org>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        linux-input@vger.kernel.org
Subject: Re: [PATCH v2] hwmon: corsair-cpro: fix ccp_probe, add delay [HID
 related]
Message-ID: <20200817153533.GA243558@roeck-us.net>
References: <20200817070040.7952-1-mail@mariuszachmann.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200817070040.7952-1-mail@mariuszachmann.de>
User-Agent: Mutt/1.9.4 (2018-02-28)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Aug 17, 2020 at 09:00:40AM +0200, Marius Zachmann wrote:
> Possibly because of the changes in usbhid/hid-core.c the first
> raw input report is not received during ccp_probe function and it will
> timeout. I am not sure, whether this behaviour is expected after
> hid_device_io_start or if I am missing something.
> As a solution this adds msleep(50) to ccp_probe so that all initial
> input reports can be received.
> 
> Signed-off-by: Marius Zachmann <mail@mariuszachmann.de>

Let's just ask the HID maintainers. Is this expected, and the correct fix ?

Thanks,
Guenter

> ---
> v2:
> - fix accidentally deleted comment
> 
> ---
>  drivers/hwmon/corsair-cpro.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/hwmon/corsair-cpro.c b/drivers/hwmon/corsair-cpro.c
> index 591929ec217a..c04fac1d820f 100644
> --- a/drivers/hwmon/corsair-cpro.c
> +++ b/drivers/hwmon/corsair-cpro.c
> @@ -10,6 +10,7 @@
> 
>  #include <linux/bitops.h>
>  #include <linux/completion.h>
> +#include <linux/delay.h>
>  #include <linux/hid.h>
>  #include <linux/hwmon.h>
>  #include <linux/kernel.h>
> @@ -513,6 +514,7 @@ static int ccp_probe(struct hid_device *hdev, const struct hid_device_id *id)
>  	init_completion(&ccp->wait_input_report);
> 
>  	hid_device_io_start(hdev);
> +	msleep(50); /* wait before events can be received */
> 
>  	/* temp and fan connection status only updates when device is powered on */
>  	ret = get_temp_cnct(ccp);
> --
> 2.28.0