From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2D162C25B67 for ; Mon, 23 Oct 2023 23:36:03 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qv4S2-0003ZT-9j; Mon, 23 Oct 2023 19:35:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qv4S0-0003Yx-10; Mon, 23 Oct 2023 19:35:12 -0400 Received: from pi.codeconstruct.com.au ([203.29.241.158] helo=codeconstruct.com.au) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qv4Rv-0000p4-T8; Mon, 23 Oct 2023 19:35:11 -0400 Received: from [192.168.68.112] (ppp118-210-136-142.adl-adc-lon-bras33.tpg.internode.on.net [118.210.136.142]) by mail.codeconstruct.com.au (Postfix) with ESMTPSA id 73DD320059; Tue, 24 Oct 2023 07:34:52 +0800 (AWST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codeconstruct.com.au; s=2022a; t=1698104094; bh=PrhhsoMwtf7fni5RNvl4eHhvdLaa5t3ue7ZCbGm1iBc=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=PHvz62yjnvJQvReGzOCwQfQrhQ91nbaIjxddpgt26uJzAYv12YWPn3Q2GAVBiMfS4 lsFDYzOkWuu+cmn5Mx04UGmQQMRxAGBlNBXX+kays6F9pyOEvf1P4QSDYmSkHPGs+h +fTcgI09QMKnSlOYXYhMBpIXDGlEPRV3HbyZ9mMrNYlNvHJt9g6CDwAKj8ogpJsiTs l+fMUgPd6jtyf+Vx16LXEdgzrG4MG0Lrs/6kMz4mjuTH38eMFKGTaL6hPlCyEtHT+u P/+ydKFDBYPaMPrRyAvNJlq2jbtVKnxjGbZgqeA2DusDn/ttB3NvUUZkKUCzMl8FaF P/Rm+tMTaPzQw== Message-ID: <47ec73eb44a8b5f5cd894f97d1e88677845cbd7a.camel@codeconstruct.com.au> Subject: Re: [PATCH 1/2] misc/pca9552: Fix inverted input status From: Andrew Jeffery To: Miles Glenn , Philippe =?ISO-8859-1?Q?Mathieu-Daud=E9?= , qemu-devel@nongnu.org Cc: qemu-arm@nongnu.org, =?ISO-8859-1?Q?C=E9dric?= Le Goater , Joel Stanley , f4bug@amsat.org Date: Tue, 24 Oct 2023 10:04:51 +1030 In-Reply-To: <53fccc103ab72cfd93e98fd28bd0a869a43b6a83.camel@linux.vnet.ibm.com> References: <20231019204011.3174115-1-milesg@linux.vnet.ibm.com> <20231019204011.3174115-2-milesg@linux.vnet.ibm.com> <01edf713-6bec-adec-5fa5-5195b5dd4273@linaro.org> <53fccc103ab72cfd93e98fd28bd0a869a43b6a83.camel@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.46.4-2 MIME-Version: 1.0 Received-SPF: pass client-ip=203.29.241.158; envelope-from=andrew@codeconstruct.com.au; helo=codeconstruct.com.au X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, 2023-10-20 at 11:32 -0500, Miles Glenn wrote: > On Fri, 2023-10-20 at 11:42 +0200, Philippe Mathieu-Daud=C3=A9 wrote: > > On 20/10/23 04:51, Andrew Jeffery wrote: > > > On Thu, 2023-10-19 at 15:40 -0500, Glenn Miles wrote: > > > > > The pca9552 INPUT0 and INPUT1 registers are supposed to > > > > > hold the logical values of the LED pins. A logical 0 > > > > > should be seen in the INPUT0/1 registers for a pin when > > > > > its corresponding LSn bits are set to 0, which is also > > > > > the state needed for turning on an LED in a typical > > > > > usage scenario. Existing code was doing the opposite > > > > > and setting INPUT0/1 bit to a 1 when the LSn bit was > > > > > set to 0, so this commit fixes that. > > > > >=20 > > > > > Signed-off-by: Glenn Miles > > > > > --- > > > > >=20 > > > > > Changes from prior version: > > > > > - Added comment regarding pca953X > > > > > - Added cover letter > > > > >=20 > > > > > hw/misc/pca9552.c | 18 +++++++++++++----- > > > > > tests/qtest/pca9552-test.c | 6 +++--- > > > > > 2 files changed, 16 insertions(+), 8 deletions(-) > > > > >=20 > > > > > diff --git a/hw/misc/pca9552.c b/hw/misc/pca9552.c > > > > > index fff19e369a..445f56a9e8 100644 > > > > > --- a/hw/misc/pca9552.c > > > > > +++ b/hw/misc/pca9552.c > > > > > @@ -36,7 +36,10 @@ typedef struct PCA955xClass PCA955xClass; > > > > > =20 > > > > > DECLARE_CLASS_CHECKERS(PCA955xClass, PCA955X, > > > > > TYPE_PCA955X) > > > > > - > > > > > +/* > > > > > + * Note: The LED_ON and LED_OFF configuration values for the > > > > > PCA955X > > > > > + * chips are the reverse of the PCA953X family of > > > > > chips. > > > > > + */ > > > > > #define PCA9552_LED_ON 0x0 > > > > > #define PCA9552_LED_OFF 0x1 > > > > > #define PCA9552_LED_PWM0 0x2 > > > > > @@ -112,13 +115,18 @@ static void > > > > > pca955x_update_pin_input(PCA955xState *s) > > > > > =20 > > > > > switch (config) { > > > > > case PCA9552_LED_ON: > > > > > - qemu_set_irq(s->gpio[i], 1); > > > > > - s->regs[input_reg] |=3D 1 << input_shift; > > > > > - break; > > > > > - case PCA9552_LED_OFF: > > > > > + /* Pin is set to 0V to turn on LED */ > > > > > qemu_set_irq(s->gpio[i], 0); > > > > > s->regs[input_reg] &=3D ~(1 << input_shift); > > > > > break; > > > > > + case PCA9552_LED_OFF: > > > > > + /* > > > > > + * Pin is set to Hi-Z to turn off LED and > > > > > + * pullup sets it to a logical 1. > > > > > + */ > > > > > + qemu_set_irq(s->gpio[i], 1); > > > > > + s->regs[input_reg] |=3D 1 << input_shift; > > > > > + break; > > >=20 > > > So the witherspoon-bmc machine was a user of the PCA9552 outputs as > > > LEDs. I guess its LEDs were in the wrong state the whole time? That > > > looks like the only user though, and shouldn't be negatively > > > affected. > >=20 > > Usually GPIO polarity is a machine/board property, not a device > > one. > >=20 > > We could use the LED API (hw/misc/led.h) which initialize each > > output with GpioPolarity. > >=20 >=20 > Thanks for your comments! This piqued my curiosity so I decided to > run a test with the witherspoon-bmc machine. Without my changes, I ran > the following command to turn off LED13 on the pca9552 which I had > previously set to "on": >=20 > qom-set /machine/unattached/device[18] led13 off >=20 > I had GDB connected at the time with a breakpoint set on > led_set_state() so that I could see what was happening. Due to the > inversion bug, I expected the pca9552 code to set the pin low and also > set the irq low, which it did. The connected LED's on this pca9552 > were all configured as GPIO_POLARITY_ACTIVE_LOW, so I expected that > setting the irq state low would actually turn on the LED. Instead it > turned off the LED. >=20 > Reviewing the LED code, I believe the problem lies here: >=20 > static void led_set_state_gpio_handler(void *opaque, int line, int > new_state) > { > LEDState *s =3D LED(opaque); >=20 > assert(line =3D=3D 0); > led_set_state(s, !!new_state !=3D s->gpio_active_high); > } >=20 >=20 > In my test, new_state was 0 and gpio_active_high was 0, resulting in > the boolean expression of ( 0 !=3D 0 ) which is false and results in > turning off the LED. So, this looks like a bug to me. >=20 > For another simpler example, if the LED polarity was set to > GPIO_POLARITY_ACTIVE_HIGH, then s->gpio_active_high would be 1. Then, > if we set the irq line to 1, wouldn't we expect the LED to turn on?=20 > However, as the code stands, it would actually turn the LED off. So, I > think we can remove one of the "!"'s from in front of new_state. Then, > if the LED is active high and the irq line is set high, it would turn > on the LED. Correct? Seems reasonable to me. Looks like Philippe added the LED behaviour in Fddb67f6402b8 ("hw/misc/led: Allow connecting from GPIO output"), so his input would be helpful. Perhaps send a fix for review? Andrew