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

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Wed, Jan 26, 2022 at 07:50:42PM +0000, Lad Prabhakar wrote:
> 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;

gfp_flags? Since this is used for allocation.

Thanks,
Mani

>  	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
>