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

[Timothy Pearson <tpearson@raptorengineering.com>]

----- 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.