Re: [PATCH v5 2/3] tty: serial: qcom_geni_serial: Wakeup over UART RX

From: Stephen Boyd <swboyd@chromium.org>
To: Akash Asthana <akashast@codeaurora.org>, gregkh@linuxfoundation.org
Cc: linux-arm-msm@vger.kernel.org, linux-serial@vger.kernel.org,
	mgautam@codeaurora.org, msavaliy@codeaurora.org
Subject: Re: [PATCH v5 2/3] tty: serial: qcom_geni_serial: Wakeup over UART RX
Date: Fri, 15 Nov 2019 11:41:38 -0800	[thread overview]
Message-ID: <5dceff73.1c69fb81.e286f.aa4e@mx.google.com> (raw)
In-Reply-To: <55a02d0f-2dec-2ba7-82e6-f21a8c86792a@codeaurora.org>

Quoting Akash Asthana (2019-11-15 02:00:44)
> 
> On 11/14/2019 11:10 PM, Stephen Boyd wrote:
> > Quoting Akash Asthana (2019-11-13 02:48:56)
> >> Add system wakeup capability over UART RX line for wakeup capable UART.
> >> When system is suspended, RX line act as an interrupt to wakeup system
> >> for any communication requests from peer.
> > How does the RX line get remuxed as a GPIO interrupt here? Is that
> > through some pinctrl magic in DT or just via enabling/disabling the
> > interrupt?
> Yes, For wakeup capable UART node, we have registered UART RX line with 
> TLMM interrupt controller in DT file . Example: if GPIO48 is UART RX line
> 
> interrupts-extended =  <&intc GIC_SPI 607 IRQ_TYPE_LEVEL_HIGH>,  <&tlmm 
> 48 IRQ_TYPE_EDGE_FALLING>;

Right. So is gpio48 muxed as 'uart' function forever and the interrupt
logic in tlmm is connected to that pad regardless of the function
selected? I thought that gpios through TLMM had to be muxed as function
0, i.e. gpio function, so that interrupts worked. But maybe that's wrong
and it can work without that.