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serial: 8250_dw: Decouple DLF register check from UCV
Designware UART has an optional feature to enable Fractional Baud Rate Divisor (DLF) through the FRACTIONAL_BAUD_DIVISOR_EN configuration parameter, and it is not dependent on ADDITIONAL_FEATURES. dw8250_setup_port() checks DLF to determine dlf_size only when UART Component Version (UCV) is non-zero. As mentioned above DLF and UCV are independent features. Move the logic corresponding to DLF size calculation ahead of the UCV check to prevent early return. Otherwise, dlf_size will be zero and driver will not be able to use the controller's fractional baud rate divisor (DLF) feature. Signed-off-by: Vamshi Gajjela <vamshigajjela@google.com> Link: https://lore.kernel.org/r/20231126160420.2442330-1-vamshigajjela@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1 changed files with 11 additions and 11 deletions
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@ -259,17 +259,6 @@ void dw8250_setup_port(struct uart_port *p)
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}
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up->capabilities |= UART_CAP_NOTEMT;
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/*
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* If the Component Version Register returns zero, we know that
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* ADDITIONAL_FEATURES are not enabled. No need to go any further.
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*/
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reg = dw8250_readl_ext(p, DW_UART_UCV);
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if (!reg)
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return;
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dev_dbg(p->dev, "Designware UART version %c.%c%c\n",
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(reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff);
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/* Preserve value written by firmware or bootloader */
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old_dlf = dw8250_readl_ext(p, DW_UART_DLF);
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dw8250_writel_ext(p, DW_UART_DLF, ~0U);
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@ -282,6 +271,17 @@ void dw8250_setup_port(struct uart_port *p)
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p->set_divisor = dw8250_set_divisor;
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}
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/*
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* If the Component Version Register returns zero, we know that
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* ADDITIONAL_FEATURES are not enabled. No need to go any further.
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*/
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reg = dw8250_readl_ext(p, DW_UART_UCV);
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if (!reg)
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return;
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dev_dbg(p->dev, "Designware UART version %c.%c%c\n",
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(reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff);
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reg = dw8250_readl_ext(p, DW_UART_CPR);
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if (!reg) {
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reg = data->pdata->cpr_val;
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