Message ID | 20231231182951.877805-1-vamshigajjela@google.com |
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State | New |
Headers |
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Series |
serial: 8250_dw: Do not bailout on UCV read returning zero
|
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Commit Message
Vamshi Gajjela
Dec. 31, 2023, 6:29 p.m. UTC
Designware UART has optional feature FIFO_MODE to implement FIFO.
Encoding FIFO capabilities through Component Parameter Register CPR is
optional and it can be enabled using parameter UART_ADD_ENCODED_PARAMS.
Driver can exercise fifo capabilities by decoding CPR if implemented
or from cpr_val provided from the dw8250_platform_data otherwise.
dw8250_setup_port() checks for CPR or cpr_val to determine FIFO size
only when Component Version (UCV) is non-zero. Bailing out early on UCV
read returning zero will leave fifosize as zero and !UART_CAP_FIFO,
hence prevent early return and continue to process CPR or cpr_val for
the driver to utilize FIFO.
Non-zero UCV implies ADDITIONAL_FEATURES=1, preventing early return
will not be an overhead here.
Signed-off-by: Vamshi Gajjela <vamshigajjela@google.com>
---
drivers/tty/serial/8250/8250_dwlib.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_dwlib.c b/drivers/tty/serial/8250/8250_dwlib.c index 136ad093c5b6..3e33ddf7bc80 100644 --- a/drivers/tty/serial/8250/8250_dwlib.c +++ b/drivers/tty/serial/8250/8250_dwlib.c @@ -271,16 +271,10 @@ void dw8250_setup_port(struct uart_port *p) p->set_divisor = dw8250_set_divisor; } - /* - * If the Component Version Register returns zero, we know that - * ADDITIONAL_FEATURES are not enabled. No need to go any further. - */ reg = dw8250_readl_ext(p, DW_UART_UCV); - if (!reg) - return; - - dev_dbg(p->dev, "Designware UART version %c.%c%c\n", - (reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff); + if (reg) + dev_dbg(p->dev, "Designware UART version %c.%c%c\n", + (reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff); reg = dw8250_readl_ext(p, DW_UART_CPR); if (!reg) {