Re: [PATCH 2/3] aspeed/pinctrl: Fix simultaneous RS-232 / PWM and DVO outputs on AST2500 devices

[Andrew Jeffery <andrew@aj.id.au>]

On Thu, 2 May 2019, at 14:29, Ryan Chen wrote:
> > ----- Original Message -----
> > > From: "Ryan Chen" <ryan_chen@aspeedtech.com>
> > > To: "Andrew Jeffery" <andrew@aj.id.au>, "Timothy Pearson" <tpearson@raptorengineering.com>, "linux-aspeed"
> > > <linux-aspeed@lists.ozlabs.org>
> > > Cc: "Morris Mao" <morris_mao@aspeedtech.com>
> > > Sent: Wednesday, May 1, 2019 10:06:25 PM
> > > Subject: RE: [PATCH 2/3] aspeed/pinctrl: Fix simultaneous RS-232 / 
> > > PWM and DVO outputs on AST2500 devices
> > 
> > >>On Thu, 2 May 2019, at 08:20, Timothy Pearson wrote:
> > >> There appears to be a small error in the pinmux table on pages 130 
> > >>and
> > >> 131 of the AST2500 datasheet v1.6.  Specifically, the COND2 
> > >>requirement used to mux the surrounding pins to DVI was 
> > >>inadvertently replicated to pins V1, W1, V2, and W2 in the table, 
> > >>which do not incorporate DVI functionality.
> > >> 
> > >> As a result of this error, both serial TX lines and the PWM 0/1 
> > >> outputs were overriding the VPO pinmux settings when VPO was 
> > >> enabled in the pinmux hogs.
> > >> 
> > >> This patch has been verified to function on Blackbird hardware.  
> > >> Both serial TXD pins and PWM0/PWM1 were functionally tested with 
> > >> SCU94[1:0] set to 0x1.
> > > 
> > > Hello Tim.
> > > 
> > > The AST2500 pwm0/1 configure need following condition, the 
> > > SCU94[1:0] is 0x1, it should not work.
> > > Could you help confirm it?
> > > 
> > > v2 : pwm 0 : scu88[0] = 1 & scu 94[1:0] = 0 & scu90[5] = 0
> > > w2 : pwm 1 : scu88[1] = 1 & scu 94[1:0] = 0 & scu90[5] = 0
> > 
> > >>I can confirm that with SCU94[1:0] == 0x1 the PWM0 and PWM1 outputs work correctly -- this was tested on our Blackbird >>hardware.  If you are reading from the datasheet, I suspect there are a few errors in it relating to the relatively rarely used DVO >>mux settings.
> > 
> > Yes it can work after check with designer, if you don't enable the CRT 
> > driver, it will work.
> > But for safety.
> 
> >>What do you mean by "for safety"?
> 
> Sorry, my point is if gfx driver also loaded, it will impact.
> But, It is ok for this modification. 

Okay, that's enough confirmation for the moment.

> Due to pinctrl gfx pwm is separate 
> driver setting. 
> 
> 
> > You need also and with COND2 for pwm driver loaded.
> 
> >>I'm confused here because it sounds like from Tim's experiment PWM0 / PWM1 work without the dependency on COND2 >>despite VPO being enabled, and the designer confirms as much, but we shouldn't do it?
> 
> >>Regardless, in summary you're saying that for TXD1 and RXD1 the change to remove the dependence on COND2 is appropriate, but not for PWM0 and PWM1?
> 
> > 
> > 
> >
>