Messages in this thread | | | From | Andy Shevchenko <> | Date | Mon, 7 Mar 2022 00:07:44 +0200 | Subject | Re: [PATCH 1/7] serial: 8250_dwlib: RS485 HW half duplex support |
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On Mon, Mar 7, 2022 at 12:00 AM Lukas Wunner <lukas@wunner.de> wrote: > On Wed, Mar 02, 2022 at 11:56:00AM +0200, Ilpo Järvinen wrote:
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> Does the DesignWare UART use dedicated DE and RE pins instead of > the RTS pin? That would be quite unusual.
They are muxed with other UART pins on SoC level, but I don't remember by heart which ones. According to the Synopsys datasheet they are separate signals. It might be that I'm missing something, since the last time I looked was last year.
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> > + d->hw_rs485_support = device_property_read_bool(p->dev, "snps,rs485-interface-en"); > > + if (d->hw_rs485_support) > > + p->rs485_config = dw8250_rs485_config; > > + > > You wrote in the commit message that rs485 support is present from > version 4.0 onward. Can't we just check the IP version and enable > rs485 support for >= 4.0? That would seem more appropriate instead > of introducing yet another new property.
AFAIU this is dependent on the IP syntheses. I.o.w. version 4.0+ is a prerequisite, but doesn't automatically mean that there is a support. Unfortunately there is no way to tell this clearly in the IP configuration register.
-- With Best Regards, Andy Shevchenko
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