Re: [PATCH 1/2] misc/pca9552: Fix inverted input status

[Andrew Jeffery]

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.
> > 
> > Signed-off-by: Glenn Miles <milesg@linux.vnet.ibm.com>
> > ---
> > 
> > Changes from prior version:
> >     - Added comment regarding pca953X
> >     - Added cover letter
> > 
> >  hw/misc/pca9552.c          | 18 +++++++++++++-----
> >  tests/qtest/pca9552-test.c |  6 +++---
> >  2 files changed, 16 insertions(+), 8 deletions(-)
> > 
> > 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;
> >  
> >  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)
> >  
> >          switch (config) {
> >          case PCA9552_LED_ON:
> > -            qemu_set_irq(s->gpio[i], 1);
> > -            s->regs[input_reg] |= 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] &= ~(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] |= 1 << input_shift;
> > +            break;

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.

Reviewed-by: Andrew Jeffery <andrew@codeconstruct.com.au>

> >          case PCA9552_LED_PWM0:
> >          case PCA9552_LED_PWM1:
> >              /* TODO */
> > diff --git a/tests/qtest/pca9552-test.c b/tests/qtest/pca9552-test.c
> > index d80ed93cd3..ccca2b3d91 100644
> > --- a/tests/qtest/pca9552-test.c
> > +++ b/tests/qtest/pca9552-test.c
> > @@ -60,7 +60,7 @@ static void send_and_receive(void *obj, void *data, 
> > QGuestAllocator *alloc)
> >      g_assert_cmphex(value, ==, 0x55);
> >  
> >      value = i2c_get8(i2cdev, PCA9552_INPUT0);
> > -    g_assert_cmphex(value, ==, 0x0);
> > +    g_assert_cmphex(value, ==, 0xFF);
> >  
> >      pca9552_init(i2cdev);
> >  
> > @@ -68,13 +68,13 @@ static void send_and_receive(void *obj, void *data, 
> > QGuestAllocator *alloc)
> >      g_assert_cmphex(value, ==, 0x54);
> >  
> >      value = i2c_get8(i2cdev, PCA9552_INPUT0);
> > -    g_assert_cmphex(value, ==, 0x01);
> > +    g_assert_cmphex(value, ==, 0xFE);
> >  
> >      value = i2c_get8(i2cdev, PCA9552_LS3);
> >      g_assert_cmphex(value, ==, 0x54);
> >  
> >      value = i2c_get8(i2cdev, PCA9552_INPUT1);
> > -    g_assert_cmphex(value, ==, 0x10);
> > +    g_assert_cmphex(value, ==, 0xEF);
> >  }
> >  
> >  static void pca9552_register_nodes(void)