[RFC PATCH 4/5] misc: pci_endpoint_test: Add support to pass flags for buffer allocation

[Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>]

By default GFP_KERNEL flag is used for buffer allocation in read, write
and copy test and then later mapped using streaming DMA api. But on
Renesas RZ/G2{EHMN} platforms using the default flag causes the tests to
fail. Allocating the buffers from DMA zone (using the GFP_DMA flag) make
the test cases to pass.

To handle such case add flags as part of struct pci_endpoint_test_data
so that platforms can pass the required flags based on the requirement.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
Hi All,

This patch is based on the conversation where switching to streaming
DMA api causes read/write/copy tests to fail on Renesas RZ/G2 platforms
when buffers are allocated using GFP_KERNEL.

[0] https://www.spinics.net/lists/linux-pci/msg92385.html

Cheers,
Prabhakar
---
 drivers/misc/pci_endpoint_test.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
index 0a00d45830e9..974546992c5e 100644
--- a/drivers/misc/pci_endpoint_test.c
+++ b/drivers/misc/pci_endpoint_test.c
@@ -117,6 +117,7 @@ struct pci_endpoint_test {
 	enum pci_barno test_reg_bar;
 	size_t alignment;
 	size_t dmac_data_alignment;
+	gfp_t flags;
 	const char *name;
 };
 
@@ -125,6 +126,7 @@ struct pci_endpoint_test_data {
 	size_t alignment;
 	int irq_type;
 	size_t dmac_data_alignment;
+	gfp_t flags;
 };
 
 static inline u32 pci_endpoint_test_readl(struct pci_endpoint_test *test,
@@ -381,7 +383,7 @@ static bool pci_endpoint_test_copy(struct pci_endpoint_test *test,
 		goto err;
 	}
 
-	orig_src_addr = kzalloc(size + alignment, GFP_KERNEL);
+	orig_src_addr = kzalloc(size + alignment, test->flags);
 	if (!orig_src_addr) {
 		dev_err(dev, "Failed to allocate source buffer\n");
 		ret = false;
@@ -414,7 +416,7 @@ static bool pci_endpoint_test_copy(struct pci_endpoint_test *test,
 
 	src_crc32 = crc32_le(~0, src_addr, size);
 
-	orig_dst_addr = kzalloc(size + alignment, GFP_KERNEL);
+	orig_dst_addr = kzalloc(size + alignment, test->flags);
 	if (!orig_dst_addr) {
 		dev_err(dev, "Failed to allocate destination address\n");
 		ret = false;
@@ -518,7 +520,7 @@ static bool pci_endpoint_test_write(struct pci_endpoint_test *test,
 		goto err;
 	}
 
-	orig_addr = kzalloc(size + alignment, GFP_KERNEL);
+	orig_addr = kzalloc(size + alignment, test->flags);
 	if (!orig_addr) {
 		dev_err(dev, "Failed to allocate address\n");
 		ret = false;
@@ -619,7 +621,7 @@ static bool pci_endpoint_test_read(struct pci_endpoint_test *test,
 		goto err;
 	}
 
-	orig_addr = kzalloc(size + alignment, GFP_KERNEL);
+	orig_addr = kzalloc(size + alignment, test->flags);
 	if (!orig_addr) {
 		dev_err(dev, "Failed to allocate destination address\n");
 		ret = false;
@@ -788,6 +790,7 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
 	test->alignment = 0;
 	test->pdev = pdev;
 	test->irq_type = IRQ_TYPE_UNDEFINED;
+	test->flags = GFP_KERNEL;
 
 	if (no_msi)
 		irq_type = IRQ_TYPE_LEGACY;
@@ -799,6 +802,7 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
 		test->alignment = data->alignment;
 		irq_type = data->irq_type;
 		test->dmac_data_alignment = data->dmac_data_alignment;
+		test->flags = data->flags;
 	}
 
 	init_completion(&test->irq_raised);
@@ -947,23 +951,27 @@ static const struct pci_endpoint_test_data default_data = {
 	.test_reg_bar = BAR_0,
 	.alignment = SZ_4K,
 	.irq_type = IRQ_TYPE_MSI,
+	.flags = GFP_KERNEL,
 };
 
 static const struct pci_endpoint_test_data am654_data = {
 	.test_reg_bar = BAR_2,
 	.alignment = SZ_64K,
 	.irq_type = IRQ_TYPE_MSI,
+	.flags = GFP_KERNEL,
 };
 
 static const struct pci_endpoint_test_data j721e_data = {
 	.alignment = 256,
 	.irq_type = IRQ_TYPE_MSI,
+	.flags = GFP_KERNEL,
 };
 
 static const struct pci_endpoint_test_data renesas_rzg2x_data = {
 	.test_reg_bar = BAR_0,
 	.irq_type = IRQ_TYPE_MSI,
 	.dmac_data_alignment = 8,
+	.flags = GFP_KERNEL | GFP_DMA,
 };
 
 static const struct pci_device_id pci_endpoint_test_tbl[] = {
-- 
2.25.1