Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 5e08f26..e5ed4ab 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -603,7 +603,7 @@
 
 	sport->tx_bytes = uart_circ_chars_pending(xmit);
 
-	if (xmit->tail < xmit->head) {
+	if (xmit->tail < xmit->head || xmit->head == 0) {
 		sport->dma_tx_nents = 1;
 		sg_init_one(sgl, xmit->buf + xmit->tail, sport->tx_bytes);
 	} else {
@@ -619,7 +619,7 @@
 		dev_err(dev, "DMA mapping error for TX.\n");
 		return;
 	}
-	desc = dmaengine_prep_slave_sg(chan, sgl, sport->dma_tx_nents,
+	desc = dmaengine_prep_slave_sg(chan, sgl, ret,
 					DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT);
 	if (!desc) {
 		dma_unmap_sg(dev, sgl, sport->dma_tx_nents,
@@ -700,22 +700,33 @@
 	}
 }
 
-static irqreturn_t imx_uart_rtsint(int irq, void *dev_id)
+static irqreturn_t __imx_uart_rtsint(int irq, void *dev_id)
 {
 	struct imx_port *sport = dev_id;
 	u32 usr1;
 
-	spin_lock(&sport->port.lock);
-
 	imx_uart_writel(sport, USR1_RTSD, USR1);
 	usr1 = imx_uart_readl(sport, USR1) & USR1_RTSS;
 	uart_handle_cts_change(&sport->port, !!usr1);
 	wake_up_interruptible(&sport->port.state->port.delta_msr_wait);
 
-	spin_unlock(&sport->port.lock);
 	return IRQ_HANDLED;
 }
 
+static irqreturn_t imx_uart_rtsint(int irq, void *dev_id)
+{
+	struct imx_port *sport = dev_id;
+	irqreturn_t ret;
+
+	spin_lock(&sport->port.lock);
+
+	ret = __imx_uart_rtsint(irq, dev_id);
+
+	spin_unlock(&sport->port.lock);
+
+	return ret;
+}
+
 static irqreturn_t imx_uart_txint(int irq, void *dev_id)
 {
 	struct imx_port *sport = dev_id;
@@ -726,14 +737,12 @@
 	return IRQ_HANDLED;
 }
 
-static irqreturn_t imx_uart_rxint(int irq, void *dev_id)
+static irqreturn_t __imx_uart_rxint(int irq, void *dev_id)
 {
 	struct imx_port *sport = dev_id;
 	unsigned int rx, flg, ignored = 0;
 	struct tty_port *port = &sport->port.state->port;
 
-	spin_lock(&sport->port.lock);
-
 	while (imx_uart_readl(sport, USR2) & USR2_RDR) {
 		u32 usr2;
 
@@ -792,11 +801,25 @@
 	}
 
 out:
-	spin_unlock(&sport->port.lock);
 	tty_flip_buffer_push(port);
+
 	return IRQ_HANDLED;
 }
 
+static irqreturn_t imx_uart_rxint(int irq, void *dev_id)
+{
+	struct imx_port *sport = dev_id;
+	irqreturn_t ret;
+
+	spin_lock(&sport->port.lock);
+
+	ret = __imx_uart_rxint(irq, dev_id);
+
+	spin_unlock(&sport->port.lock);
+
+	return ret;
+}
+
 static void imx_uart_clear_rx_errors(struct imx_port *sport);
 
 /*
@@ -854,6 +877,14 @@
 	struct imx_port *sport = dev_id;
 	unsigned int usr1, usr2, ucr1, ucr2, ucr3, ucr4;
 	irqreturn_t ret = IRQ_NONE;
+	unsigned long flags = 0;
+
+	/*
+	 * IRQs might not be disabled upon entering this interrupt handler,
+	 * e.g. when interrupt handlers are forced to be threaded. To support
+	 * this scenario as well, disable IRQs when acquiring the spinlock.
+	 */
+	spin_lock_irqsave(&sport->port.lock, flags);
 
 	usr1 = imx_uart_readl(sport, USR1);
 	usr2 = imx_uart_readl(sport, USR2);
@@ -888,27 +919,25 @@
 		usr2 &= ~USR2_ORE;
 
 	if (usr1 & (USR1_RRDY | USR1_AGTIM)) {
-		imx_uart_rxint(irq, dev_id);
+		__imx_uart_rxint(irq, dev_id);
 		ret = IRQ_HANDLED;
 	}
 
 	if ((usr1 & USR1_TRDY) || (usr2 & USR2_TXDC)) {
-		imx_uart_txint(irq, dev_id);
+		imx_uart_transmit_buffer(sport);
 		ret = IRQ_HANDLED;
 	}
 
 	if (usr1 & USR1_DTRD) {
 		imx_uart_writel(sport, USR1_DTRD, USR1);
 
-		spin_lock(&sport->port.lock);
 		imx_uart_mctrl_check(sport);
-		spin_unlock(&sport->port.lock);
 
 		ret = IRQ_HANDLED;
 	}
 
 	if (usr1 & USR1_RTSD) {
-		imx_uart_rtsint(irq, dev_id);
+		__imx_uart_rtsint(irq, dev_id);
 		ret = IRQ_HANDLED;
 	}
 
@@ -923,6 +952,8 @@
 		ret = IRQ_HANDLED;
 	}
 
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+
 	return ret;
 }
 
@@ -1911,16 +1942,6 @@
 	unsigned int ucr1;
 	unsigned long flags = 0;
 	int locked = 1;
-	int retval;
-
-	retval = clk_enable(sport->clk_per);
-	if (retval)
-		return;
-	retval = clk_enable(sport->clk_ipg);
-	if (retval) {
-		clk_disable(sport->clk_per);
-		return;
-	}
 
 	if (sport->port.sysrq)
 		locked = 0;
@@ -1956,9 +1977,6 @@
 
 	if (locked)
 		spin_unlock_irqrestore(&sport->port.lock, flags);
-
-	clk_disable(sport->clk_ipg);
-	clk_disable(sport->clk_per);
 }
 
 /*
@@ -2059,15 +2077,14 @@
 
 	retval = uart_set_options(&sport->port, co, baud, parity, bits, flow);
 
-	clk_disable(sport->clk_ipg);
 	if (retval) {
-		clk_unprepare(sport->clk_ipg);
+		clk_disable_unprepare(sport->clk_ipg);
 		goto error_console;
 	}
 
-	retval = clk_prepare(sport->clk_per);
+	retval = clk_prepare_enable(sport->clk_per);
 	if (retval)
-		clk_unprepare(sport->clk_ipg);
+		clk_disable_unprepare(sport->clk_ipg);
 
 error_console:
 	return retval;