[PATCH v9 3/5] Input: synaptics-rmi4 - don't do unaligned reads in IRQ context

[David Heidelberg via B4 Relay]

From: Kaustabh Chakraborty <kauschluss@xxxxxxxxxxx>

Some replacement displays include third-party touch ICs which incur a
significant penalty (1-2 seconds) when doing certain unaligned reads.
This is enough to break functionality when it happens in the hot path,
so adjust the interrupt handler to not read from an unaligned address.

Signed-off-by: Kaustabh Chakraborty <kauschluss@xxxxxxxxxxx>
Signed-off-by: Casey Connolly <casey.connolly@xxxxxxxxxx>
Signed-off-by: David Heidelberg <david@xxxxxxx>
---
 drivers/input/rmi4/rmi_driver.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
index 3edec5ae1f8c9..5e7766363aa23 100644
--- a/drivers/input/rmi4/rmi_driver.c
+++ b/drivers/input/rmi4/rmi_driver.c
@@ -133,19 +133,24 @@ static int rmi_process_interrupt_requests(struct rmi_device *rmi_dev)
 	struct device *dev = &rmi_dev->dev;
 	int i;
 	int error;
 
 	if (!data)
 		return 0;
 
 	if (!data->attn_data.data) {
+		/*
+		 * Read the device status register as well and ignore it.
+		 * Some aftermarket ICs have issues with interrupt requests
+		 * otherwise.
+		 */
 		error = rmi_read_block(rmi_dev,
-				data->f01_container->fd.data_base_addr + 1,
-				data->irq_status, data->num_of_irq_regs);
+				data->f01_container->fd.data_base_addr,
+				(u8 *)data->irq_status - 1, data->num_of_irq_regs + 1);
 		if (error < 0) {
 			dev_err(dev, "Failed to read irqs, code=%d\n", error);
 			return error;
 		}
 	}
 
 	mutex_lock(&data->irq_mutex);
 	bitmap_and(data->irq_status, data->irq_status, data->fn_irq_bits,
@@ -1117,26 +1122,27 @@ int rmi_probe_interrupts(struct rmi_driver_data *data)
 		dev_err(&rmi_dev->dev, "Failed to create IRQ domain\n");
 		return -ENOMEM;
 	}
 
 	data->irq_count = irq_count;
 	data->num_of_irq_regs = (data->irq_count + 7) / 8;
 
 	size = BITS_TO_LONGS(data->irq_count) * sizeof(unsigned long);
-	data->irq_memory = devm_kcalloc(dev, size, 4, GFP_KERNEL);
+	data->irq_memory = devm_kzalloc(dev, size * 4 + 1, GFP_KERNEL);
 	if (!data->irq_memory) {
 		dev_err(dev, "Failed to allocate memory for irq masks.\n");
 		return -ENOMEM;
 	}
 
-	data->irq_status	= data->irq_memory + size * 0;
-	data->fn_irq_bits	= data->irq_memory + size * 1;
-	data->current_irq_mask	= data->irq_memory + size * 2;
-	data->new_irq_mask	= data->irq_memory + size * 3;
+	/* The first byte is reserved for the device status register */
+	data->irq_status	= data->irq_memory + size * 0 + 1;
+	data->fn_irq_bits	= data->irq_memory + size * 1 + 1;
+	data->current_irq_mask	= data->irq_memory + size * 2 + 1;
+	data->new_irq_mask	= data->irq_memory + size * 3 + 1;
 
 	return retval;
 }
 
 int rmi_init_functions(struct rmi_driver_data *data)
 {
 	struct rmi_device *rmi_dev = data->rmi_dev;
 	struct device *dev = &rmi_dev->dev;

-- 
2.53.0