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