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Re: [PATCH v5 5/7] hw/misc/mps2-fpgaio: Use the LED device


From: Philippe Mathieu-Daudé
Subject: Re: [PATCH v5 5/7] hw/misc/mps2-fpgaio: Use the LED device
Date: Sat, 12 Sep 2020 10:06:55 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0

On 9/11/20 10:12 PM, Luc Michel wrote:
> Hi Phil,
> 
> On 9/10/20 10:54 PM, Philippe Mathieu-Daudé wrote:
>> Per the 'ARM MPS2 and MPS2+ FPGA Prototyping Boards Technical
>> Reference Manual' (100112_0200_07_en):
>>
>>    2.1  Overview of the MPS2 and MPS2+ hardware
>>
>>         The MPS2 and MPS2+ FPGA Prototyping Boards contain the
>>         following components and interfaces:
>>
>>         * User switches and user LEDs:
>>
>>           - Two green LEDs and two push buttons that connect to
>>             the FPGA.
>>           - Eight green LEDs and one 8-way dip switch that connect
>>             to the MCC.
>>
>> Add the 2 LEDs connected to the FPGA.
>>
>> This remplaces the 'mps2_fpgaio_leds' trace events by the generic
> replaces
>> 'led_set_intensity' event.
> 
> If I'm not mistaken the LED device being a DEVICE and not a
> SYS_BUS_DEVICE, it needs to be manually reset. So you probably need to
> reset it in mps2_fpgaio_reset so it doesn't get out of sync on system
> reset.

Correct...

Alternatively we could see a LED as a SysBusDevice exposing a MMIO
region of 1 writable bit =) But it is unlikely to be mapped on the
main system bus.

I'll add the reset, thanks for reviewing!

Phil.



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