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When a serial port is configured for RTS/CTS flow control, serial core will disable the transmitter if it observes CTS is de-asserted. This is perfectly reasonable and appropriate when the UART lacks the ability to automatically perform CTS flow control. However, if the UART hardware can manage flow control automatically, it is important that software not get involved. When the DesignWare UART enables 16C750 style auto-RTS/CTS it stops generating interrupts for changes in CTS state so software mostly stays out of the way. However, it does report the true state of CTS in the MSR so software may notice it is de-asserted and respond by improperly disabling the transmitter. Once this happens the transmitter will be blocked forever. To avoid this situation, we simply lie to the 8250 and serial core by reporting that CTS is asserted whenever auto-RTS/CTS mode is enabled. Signed-off-by: Tim Kryger <tim.kryger@linaro.org> Reviewed-by: Matt Porter <matt.porter@linaro.org> Reviewed-by: Markus Mayer <markus.mayer@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| .. | ||
| 8250_accent.c | ||
| 8250_acorn.c | ||
| 8250_boca.c | ||
| 8250_core.c | ||
| 8250_dma.c | ||
| 8250_dw.c | ||
| 8250_early.c | ||
| 8250_em.c | ||
| 8250_exar_st16c554.c | ||
| 8250_fourport.c | ||
| 8250_fsl.c | ||
| 8250_gsc.c | ||
| 8250_hp300.c | ||
| 8250_hub6.c | ||
| 8250_pci.c | ||
| 8250_pnp.c | ||
| 8250.h | ||
| Kconfig | ||
| Makefile | ||
| serial_cs.c | ||