diff options
| -rw-r--r-- | target/linux/generic/pending-5.15/860-serial-8250_mtk-track-busclk-state-to-avoid-bus-error.patch | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/target/linux/generic/pending-5.15/860-serial-8250_mtk-track-busclk-state-to-avoid-bus-error.patch b/target/linux/generic/pending-5.15/860-serial-8250_mtk-track-busclk-state-to-avoid-bus-error.patch new file mode 100644 index 0000000000..c5db5d9491 --- /dev/null +++ b/target/linux/generic/pending-5.15/860-serial-8250_mtk-track-busclk-state-to-avoid-bus-error.patch @@ -0,0 +1,61 @@ +From 629c701fc39f1ada9416e0766a86729e83bde86c Mon Sep 17 00:00:00 2001 +Message-ID: <629c701fc39f1ada9416e0766a86729e83bde86c.1694465766.git.daniel@makrotopia.org> +From: Daniel Golle <daniel@makrotopia.org> +Date: Mon, 11 Sep 2023 21:27:44 +0100 +Subject: [PATCH] serial: 8250_mtk: track busclk state to avoid bus error +To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, + Jiri Slaby <jirislaby@kernel.org>, + Matthias Brugger <matthias.bgg@gmail.com>, + AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>, + Daniel Golle <daniel@makrotopia.org>, + John Ogness <john.ogness@linutronix.de>, + Chen-Yu Tsai <wenst@chromium.org>, + Changqi Hu <changqi.hu@mediatek.com>, + linux-kernel@vger.kernel.org, + linux-serial@vger.kernel.org, + linux-arm-kernel@lists.infradead.org, + linux-mediatek@lists.infradead.org + +Commit e32a83c70cf9 ("serial: 8250-mtk: modify mtk uart power and +clock management") introduced polling a debug register to make sure +the UART is idle before disabling the bus clock. However, at least on +some MediaTek SoCs access to that very debug register requires the bus +clock being enabled. Hence calling the suspend function while already +in suspended state results in that register access triggering a bus +error. In order to avoid that, track the state of the bus clock and +only poll the debug register if not already in suspended state. + +Fixes: e32a83c70cf9 ("serial: 8250-mtk: modify mtk uart power and clock management") +Signed-off-by: Daniel Golle <daniel@makrotopia.org> +--- + drivers/tty/serial/8250/8250_mtk.c | 11 ++++++++++- + 1 file changed, 10 insertions(+), 1 deletion(-) + +--- a/drivers/tty/serial/8250/8250_mtk.c ++++ b/drivers/tty/serial/8250/8250_mtk.c +@@ -32,7 +32,7 @@ + #define MTK_UART_RXTRI_AD 0x14 /* RX Trigger address */ + #define MTK_UART_FRACDIV_L 0x15 /* Fractional divider LSB address */ + #define MTK_UART_FRACDIV_M 0x16 /* Fractional divider MSB address */ +-#define MTK_UART_DEBUG0 0x18 ++#define MTK_UART_DEBUG0 0x18 + #define MTK_UART_IER_XOFFI 0x20 /* Enable XOFF character interrupt */ + #define MTK_UART_IER_RTSI 0x40 /* Enable RTS Modem status interrupt */ + #define MTK_UART_IER_CTSI 0x80 /* Enable CTS Modem status interrupt */ +@@ -418,13 +418,12 @@ static int __maybe_unused mtk8250_runtim + struct mtk8250_data *data = dev_get_drvdata(dev); + struct uart_8250_port *up = serial8250_get_port(data->line); + +- /* wait until UART in idle status */ +- while +- (serial_in(up, MTK_UART_DEBUG0)); +- + if (data->clk_count == 0U) { + dev_dbg(dev, "%s clock count is 0\n", __func__); + } else { ++ /* wait until UART in idle status */ ++ while ++ (serial_in(up, MTK_UART_DEBUG0)); + clk_disable_unprepare(data->bus_clk); + data->clk_count--; + } |