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From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Date: Thu, 18 Apr 2024 02:01:39 +0200
Message-ID: <CACMJSet_SKVPV74AKz52LRH1PaxzF4gaFbdayCYNVW7Xt-5mnA@mail.gmail.com>
Subject: Re: [PATCH] Revert "Bluetooth: hci_qca: don't use IS_ERR_OR_NULL()
 with gpiod_get_optional()"
To: quic_zijuhu <quic_zijuhu@quicinc.com>
Cc: luiz.dentz@gmail.com, luiz.von.dentz@intel.com, marcel@holtmann.org, 
	linux-bluetooth@vger.kernel.org, wt@penguintechs.org
Content-Type: text/plain; charset="UTF-8"

On Thu, 18 Apr 2024 at 01:44, quic_zijuhu <quic_zijuhu@quicinc.com> wrote:
>
> On 4/18/2024 2:59 AM, Bartosz Golaszewski wrote:
> > On Wed, 17 Apr 2024 at 13:53, Zijun Hu <quic_zijuhu@quicinc.com> wrote:
> >>
> >> This reverts commit 56d074d26c5828773b00b2185dd7e1d08273b8e8.
> >>
> >> Commit 56d074d26c58 ("Bluetooth: hci_qca: don't use IS_ERR_OR_NULL()
> >> with gpiod_get_optional()") will cause serious regression issue for
> >> several QCA controllers such as QCA_WCN6750,QCA_WCN6855,QCA_ROME,
> >> QCA_QCA6390 and QCA_QCA2066, the regression issue is that BT can't be
> >> enabled any more once BT is disabled if BT reset pin is not configured
> >> by DT or ACPI.
> >>
> >> if BT reset pin is not configured, devm_gpiod_get_optional() will return
> >> NULL, and we should NOT set quirk HCI_QUIRK_NON_PERSISTENT_SETUP, but the
> >> reverted commit SET the quirk since NULL is not a error case, and cause
> >> qca_setup() call failure triggered by the 2nd and later BT enable
> >> operations since there are no available BT reset pin to clear BT firmware
> >> downloaded by the 1st enable operation, fixed by reverting the commit.
> >>
> >
> > Then you just go back to bad usage of the GPIO API. Please see my
> > suggestion below.
> >
> we need to treat below tow cases equivalently.
> 1) BT reset pin is NOT configured, devm_gpiod_get_optional() return NULL.
> 2) BT reset pin is configured, but failed to be got, devm_gpiod_get_optional() return ERROR.
>
> FOR above two cases, hci_qca driver doesn't get available BT reset pin for H/W reset.
> so we use IS_ERR_OR_NULL() instead of IS_ERR().
>
> is it not right ?
>
>
> >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=218726
> >> Fixes: 56d074d26c58 ("Bluetooth: hci_qca: don't use IS_ERR_OR_NULL() with gpiod_get_optional()")
> >> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
> >> ---
> >>  drivers/bluetooth/hci_qca.c | 6 +++---
> >>  1 file changed, 3 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> >> index 92fa20f5ac7d..160175a23a49 100644
> >> --- a/drivers/bluetooth/hci_qca.c
> >> +++ b/drivers/bluetooth/hci_qca.c
> >> @@ -2323,7 +2323,7 @@ static int qca_serdev_probe(struct serdev_device *serdev)
> >>
> >>                 qcadev->bt_en = devm_gpiod_get_optional(&serdev->dev, "enable",
> >>                                                GPIOD_OUT_LOW);
> >> -               if (IS_ERR(qcadev->bt_en) &&
> >> +               if (IS_ERR_OR_NULL(qcadev->bt_en) &&
> >>                     (data->soc_type == QCA_WCN6750 ||
> >>                      data->soc_type == QCA_WCN6855)) {
> >>                         dev_err(&serdev->dev, "failed to acquire BT_EN gpio\n");
> >> @@ -2332,7 +2332,7 @@ static int qca_serdev_probe(struct serdev_device *serdev)
> >>
> >>                 qcadev->sw_ctrl = devm_gpiod_get_optional(&serdev->dev, "swctrl",
> >>                                                GPIOD_IN);
> >> -               if (IS_ERR(qcadev->sw_ctrl) &&
> >> +               if (IS_ERR_OR_NULL(qcadev->sw_ctrl) &&
> >>                     (data->soc_type == QCA_WCN6750 ||
> >>                      data->soc_type == QCA_WCN6855 ||
> >>                      data->soc_type == QCA_WCN7850))
> >> @@ -2354,7 +2354,7 @@ static int qca_serdev_probe(struct serdev_device *serdev)
> >>         default:
> >>                 qcadev->bt_en = devm_gpiod_get_optional(&serdev->dev, "enable",
> >>                                                GPIOD_OUT_LOW);
> >> -               if (IS_ERR(qcadev->bt_en)) {
> >> +               if (IS_ERR_OR_NULL(qcadev->bt_en)) {
> >>                         dev_warn(&serdev->dev, "failed to acquire enable gpio\n");
> >>                         power_ctrl_enabled = false;
> >
> > Can you just move this out of this block? Or just simply check the
> > presence of the GPIO descriptor in the if block setting the quirk bit?
> > Warning on a missing *optional* GPIO is wrong. It's not an unexpected
> > situation, it's normal.
> >
> your concern is that the prompt message is printed by wrong way or the prompt message is not precise.
> is it right ?
>

Actually now that you're saying this: if gpiod_get_optional() returns
IS_ERR() then we should bail-out and return dev_err_probe(), not
proceed. What if GPIOLIB returns EPROBE_DEFER? Only NULL is an
acceptable return value from gpiod_get_optional().

Bart

> > Bartosz
> >
> >>                 }
> >> --
> >> 2.7.4
> >>
>