@@ -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) {
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(-)