Re: [PATCH v3 6/8] serial: Add Tegra Combined UART driver

Thierry Reding
2018-07-02T13:18:59Z

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On Mon, Jul 02, 2018 at 02:40:31PM +0300, Mikko Perttunen wrote:
> The Tegra Combined UART (TCU) is a mailbox-based mechanism that allows
> multiplexing multiple "virtual UARTs" into a single hardware serial
> port. The TCU is the primary serial port on Tegra194 devices.
>
> Add a TCU driver utilizing the mailbox framework, as the used mailboxes
> are part of Tegra HSP blocks that are already controlled by the Tegra
> HSP mailbox driver.
>
> Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> ---
>
> Notes:
> v2:
> - Removed (void) casts for unused variables.
> - Changed the uart_set_options() call to be on one line, even if its
> over 80 characters.
> - Added defines for magic numbers.
> - Style fixes.
> - Changed Kconfig entry to depend on the Tegra HSP driver instead of
> just the mailbox framework.
>
> v3:
> - Removed FLUSH bit, as it's unnecessary and slows down printing
> - Removed call to uart_set_options
> - Added mbox_free_channel calls to remove()
>
> drivers/tty/serial/Kconfig | 9 ++
> drivers/tty/serial/Makefile | 1 +
> drivers/tty/serial/tegra-tcu.c | 291 +++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/serial_core.h | 3 +
> 4 files changed, 304 insertions(+)
> create mode 100644 drivers/tty/serial/tegra-tcu.c

The driver looks good to me. But for my own understanding, is there some
way we can make use of the multiplexing? That is, could we add a
mechanism to have the driver filter out only a specific stream? Could we
also specify which stream to send data back to? What happens by default?
Which stream is data sent to?

Thierry

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