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[84.106.84.65]) by smtp.gmail.com with ESMTPSA id i93sm11419929wri.57.2019.08.12.10.18.46 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Mon, 12 Aug 2019 10:18:46 -0700 (PDT) Subject: Re: [PATCH] extcon-intel-cht-wc: Don't reset USB data connection at probe To: Yauhen Kharuzhy Cc: linux-kernel@vger.kernel.org, Chanwoo Choi , MyungJoo Ham , Andy Shevchenko References: <20190808220129.2737-1-jekhor@gmail.com> <20190809151116.GD30248@jeknote.loshitsa1.net> From: Hans de Goede Message-ID: <492098ce-ec4c-a860-4625-27c410d7deb3@redhat.com> Date: Mon, 12 Aug 2019 19:18:45 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190809151116.GD30248@jeknote.loshitsa1.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 09-08-19 17:11, Yauhen Kharuzhy wrote: > On Fri, Aug 09, 2019 at 01:06:01PM +0200, Hans de Goede wrote: >> Hi, >> >> On 8/9/19 12:01 AM, Yauhen Kharuzhy wrote: >>> Intel Cherry Trail Whiskey Cove extcon driver connect USB data lines to >>> PMIC at driver probing for further charger detection. This causes reset of >>> USB data sessions and removing all devices from bus. If system was >>> booted from Live CD or USB dongle, this makes system unusable. >>> >>> Check if USB ID pin is floating and re-route data lines in this case >>> only, don't touch otherwise. >>> >>> Signed-off-by: Yauhen Kharuzhy >>> --- >>> drivers/extcon/extcon-intel-cht-wc.c | 16 ++++++++++++++-- >>> 1 file changed, 14 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/extcon/extcon-intel-cht-wc.c b/drivers/extcon/extcon-intel-cht-wc.c >>> index 9d32150e68db..3ae573e93e6e 100644 >>> --- a/drivers/extcon/extcon-intel-cht-wc.c >>> +++ b/drivers/extcon/extcon-intel-cht-wc.c >>> @@ -338,6 +338,7 @@ static int cht_wc_extcon_probe(struct platform_device *pdev) >>> struct intel_soc_pmic *pmic = dev_get_drvdata(pdev->dev.parent); >>> struct cht_wc_extcon_data *ext; >>> unsigned long mask = ~(CHT_WC_PWRSRC_VBUS | CHT_WC_PWRSRC_USBID_MASK); >>> + int pwrsrc_sts, id; >>> int irq, ret; >>> irq = platform_get_irq(pdev, 0); >>> @@ -387,8 +388,19 @@ static int cht_wc_extcon_probe(struct platform_device *pdev) >>> goto disable_sw_control; >>> } >>> - /* Route D+ and D- to PMIC for initial charger detection */ >>> - cht_wc_extcon_set_phymux(ext, MUX_SEL_PMIC); >>> + ret = regmap_read(ext->regmap, CHT_WC_PWRSRC_STS, &pwrsrc_sts); >>> + if (ret) { >>> + dev_err(ext->dev, "Error reading pwrsrc status: %d\n", ret); >>> + goto disable_sw_control; >>> + } >>> + >>> + id = cht_wc_extcon_get_id(ext, pwrsrc_sts); >>> + >>> + /* If no USB host or device connected, route D+ and D- to PMIC for >>> + * initial charger detection >>> + */ >>> + if (id == INTEL_USB_ID_FLOAT) >>> + cht_wc_extcon_set_phymux(ext, MUX_SEL_PMIC); >> >> The check here should be != INTEL_USB_ID_GND, when we are connected as >> device we are charging from the host we are connected to and the port >> we are connected to may be a CDP (charging downstream port) instead of >> a SDP (standard downstream port) allowing us to charge at 1.5A instead >> of 0.5A, also != INTEL_USB_ID_GND matches the condition used in >> cht_wc_extcon_pwrsrc_event to determine if we should continue with >> charger detection there. > > Actually it should be checked as ((id != INTEL_USB_ID_GND) && (id != > INTEL_USB_RID_A)), to not interrupt connection if ACA used and our host > is OTG A device (for example, if LiveCD boots from USB flash inserted > into an ACA USB hub). Right, except that cht_wc_extcon_get_id never returns INTEL_USB_RID_A, so checking for that would be superfluous and also would be inconsistent with what cht_wc_extcon_pwrsrc_event is doing, so for now please just test for != INTEL_USB_ID_GND, if cht_wc_extcon_get_id ever starts supporting RID_A then we should fix both cht_wc_extcon_pwrsrc_event and you new check at that time. Hmm, I now see that cht_wc_extcon_get_id currently only reports one of: INTEL_USB_ID_GND or INTEL_USB_ID_FLOAT so == INTEL_USB_ID_FLOAT is equivalent to != INTEL_USB_ID_GND still please check for 1= INTEL_USB_ID_GND as that is what cht_wc_extcon_pwrsrc_event is doing. >> Like your other patch I will try to give this one a test-run tomorrow. I've given this patch a test-run today and I can confirm that BC1.2 charger detection still works fine on my device using this driver. Regards, Hans