serial: 8250_uniphier: avoid locking for FCR register write
The hardware book says, the FCR is combined with a register called CHAR (it will trigger interrupt when a specific character is received). At first, I used lock/read/modify/write/unlock dance for the FCR to not affect the upper bits, but the CHAR is actually never used. It should not hurt to always clear the CHAR and to handle the FCR as a normal case. It can save the costly locking. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Suggested-by: Denys Vlasenko <dvlasenk@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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da7fa058a3
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@ -101,7 +101,7 @@ static unsigned int uniphier_serial_in(struct uart_port *p, int offset)
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static void uniphier_serial_out(struct uart_port *p, int offset, int value)
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{
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unsigned int valshift = 0;
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bool normal = false;
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bool normal = true;
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switch (offset) {
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case UART_FCR:
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@ -114,9 +114,9 @@ static void uniphier_serial_out(struct uart_port *p, int offset, int value)
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/* fall through */
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case UART_MCR:
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offset = UNIPHIER_UART_LCR_MCR;
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normal = false;
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break;
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default:
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normal = true;
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offset <<= UNIPHIER_UART_REGSHIFT;
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break;
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}
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