X-Git-Url: http://git.openwrt.org/?a=blobdiff_plain;f=target%2Flinux%2Fbrcm2708%2Fpatches-4.19%2F950-0610-tty-amba-pl011-Make-TX-optimisation-conditional.patch;fp=target%2Flinux%2Fbrcm2708%2Fpatches-4.19%2F950-0610-tty-amba-pl011-Make-TX-optimisation-conditional.patch;h=0000000000000000000000000000000000000000;hb=84d555aa74434392b682fd9eb0fa701c89a046d6;hp=8d40afb4443fdcb92a5c8cf8502f02b4c30b9632;hpb=953973c2991e8640549a55df7a0574a1abac8644;p=openwrt%2Fstaging%2Fchunkeey.git

diff --git a/target/linux/brcm2708/patches-4.19/950-0610-tty-amba-pl011-Make-TX-optimisation-conditional.patch b/target/linux/brcm2708/patches-4.19/950-0610-tty-amba-pl011-Make-TX-optimisation-conditional.patch
deleted file mode 100644
index 8d40afb444..0000000000
--- a/target/linux/brcm2708/patches-4.19/950-0610-tty-amba-pl011-Make-TX-optimisation-conditional.patch
+++ /dev/null
@@ -1,85 +0,0 @@
-From 3e3c13488e4efa0236c47a98ee5e759bf1f7c757 Mon Sep 17 00:00:00 2001
-From: Phil Elwell <phil@raspberrypi.org>
-Date: Thu, 11 Jul 2019 13:13:39 +0100
-Subject: [PATCH] tty: amba-pl011: Make TX optimisation conditional
-
-pl011_tx_chars takes a "from_irq" parameter to reduce the number of
-register accesses. When from_irq is true the function assumes that the
-FIFO is half empty and writes up to half a FIFO's worth of bytes
-without polling the FIFO status register, the reasoning being that
-the function is being called as a result of the TX interrupt being
-raised. This logic would work were it not for the fact that
-pl011_rx_chars, called from pl011_int before pl011_tx_chars, releases
-the spinlock before calling tty_flip_buffer_push.
-
-A user thread writing to the UART claims the spinlock and ultimately
-calls pl011_tx_chars with from_irq set to false. This reverts to the
-older logic that polls the FIFO status register before sending every
-byte. If this happen on an SMP system during the section of the IRQ
-handler where the spinlock has been released, then by the time the TX
-interrupt handler is called, the FIFO may already be full, and any
-further writes are likely to be lost.
-
-The fix involves adding a per-port flag that is true iff running from
-within the interrupt handler and the spinlock has not yet been released.
-This flag is then used as the value for the from_irq parameter of
-pl011_tx_chars, causing polling to be used in the unsafe case.
-
-Fixes: 1e84d22322ce ("serial/amba-pl011: Refactor and simplify TX FIFO handling")
-
-Signed-off-by: Phil Elwell <phil@raspberrypi.org>
----
- drivers/tty/serial/amba-pl011.c | 7 ++++++-
- 1 file changed, 6 insertions(+), 1 deletion(-)
-
---- a/drivers/tty/serial/amba-pl011.c
-+++ b/drivers/tty/serial/amba-pl011.c
-@@ -270,6 +270,7 @@ struct uart_amba_port {
- 	unsigned int		old_cr;		/* state during shutdown */
- 	unsigned int		fixed_baud;	/* vendor-set fixed baud rate */
- 	char			type[12];
-+	bool			irq_locked;	/* in irq, unreleased lock */
- #ifdef CONFIG_DMA_ENGINE
- 	/* DMA stuff */
- 	bool			using_tx_dma;
-@@ -813,6 +814,7 @@ __acquires(&uap->port.lock)
- 	if (!uap->using_tx_dma)
- 		return;
- 
-+	uap->irq_locked = 0;
- 	dmaengine_terminate_async(uap->dmatx.chan);
- 
- 	if (uap->dmatx.queued) {
-@@ -939,6 +941,7 @@ static void pl011_dma_rx_chars(struct ua
- 		fifotaken = pl011_fifo_to_tty(uap);
- 	}
- 
-+	uap->irq_locked = 0;
- 	spin_unlock(&uap->port.lock);
- 	dev_vdbg(uap->port.dev,
- 		 "Took %d chars from DMA buffer and %d chars from the FIFO\n",
-@@ -1347,6 +1350,7 @@ __acquires(&uap->port.lock)
- {
- 	pl011_fifo_to_tty(uap);
- 
-+	uap->irq_locked = 0;
- 	spin_unlock(&uap->port.lock);
- 	tty_flip_buffer_push(&uap->port.state->port);
- 	/*
-@@ -1482,6 +1486,7 @@ static irqreturn_t pl011_int(int irq, vo
- 	int handled = 0;
- 
- 	spin_lock_irqsave(&uap->port.lock, flags);
-+	uap->irq_locked = 1;
- 	status = pl011_read(uap, REG_RIS) & uap->im;
- 	if (status) {
- 		do {
-@@ -1501,7 +1506,7 @@ static irqreturn_t pl011_int(int irq, vo
- 				      UART011_CTSMIS|UART011_RIMIS))
- 				pl011_modem_status(uap);
- 			if (status & UART011_TXIS)
--				pl011_tx_chars(uap, true);
-+				pl011_tx_chars(uap, uap->irq_locked);
- 
- 			if (pass_counter-- == 0)
- 				break;