Re: [PATCH v5] tty: serial: don't do termios for BTIF
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: 2020-07-08 14:58:20
Also in:
linux-mediatek, linux-serial, lkml
On Wed, Jul 08, 2020 at 07:11:22AM +0800, sean.wang@mediatek.com wrote:
From: Sean Wang <sean.wang@mediatek.com> Bluetooth Interface (BTIF) is designed dedicatedly for MediaTek SOC with BT in order to be instead of the UART interface between BT module and Host CPU, and not exported to user space to access. As the UART design, BTIF will be an APB slave and can transmit or receive data by MCU access, but doesn't provide termios function like baudrate and flow control setup. Even LCR on offset 0xC that is just a FAKELCR a. If FAKELCR[7] is equaled to 1, RBR(0x00), THR(0x00), IER(0x04) will not be readable/writable. b. If FAKELCR is equaled to 0xBF, RBR(0x00), THR(0x00), IER(0x04), IIR(0x08), and LSR(0x14) will not be readable/writable. So adding a new capability 'UART_CAP_NTIO' for the unusual unsupported case. The bluetooth driver would use BTIF device as a serdev. So the termios still function would be called in kernelspace from ttyport_open in drivers/tty/serdev/serdev-ttyprt.c.
...
up->port.quirks |= skip_txen_test ? UPQ_NO_TXEN_TEST : 0; + + if (up->port.type == PORT_MTK_BTIF) + up->port.quirks |= UPQ_IGNORE_TERMIOS;
I don't like to see this in core. Can we have this inside 8250_port.c? Something like extending struct serial8250_config to carry quirks and assign them when you add a port or start it (wherever it's appropriated)? -- With Best Regards, Andy Shevchenko _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel