linux-kernel - Re: [PATCH v5 2/5] Bluetooth: hci_qca: Deassert RTS while baudrate change command

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Message-ID: <20190118094416.GB3691@localhost>
Date:   Fri, 18 Jan 2019 10:44:16 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Johan Hovold <johan@...nel.org>,
        Balakrishna Godavarthi <bgodavar@...eaurora.org>,
        marcel@...tmann.org, johan.hedberg@...il.com,
        linux-kernel@...r.kernel.org, linux-bluetooth@...r.kernel.org,
        hemantg@...eaurora.org, linux-arm-msm@...r.kernel.org,
        Johan Hovold <jhovold@...il.com>
Subject: Re: [PATCH v5 2/5] Bluetooth: hci_qca: Deassert RTS while baudrate
 change command

On Thu, Jan 17, 2019 at 09:21:09AM -0800, Matthias Kaehlcke wrote:

> I observed that the qcom_geni_serial driver doesn't raise RTS with
> flow control disabled. It seems we have to investigate why that's the
> case. I agree that the driver should be platform agnostic.

Sounds like a driver bug, unless the hardware is just "odd". The
driver implementation of this looks very non-standard judging from a
quick peek.

In fact, qcom_geni_serial_get_mctrl() is currently a no-op if hardware
flow control is not enabled:

	if (uart_console(uport) || !uart_cts_enabled(uport))
		return;

Perhaps dropping the !uart_cts_enabled() test is sufficient.

Johan