From 70f008fb3ea9bd2e6727eebc858405acd49a212b Mon Sep 17 00:00:00 2001 From: Amelie Delaunay Date: Fri, 24 Nov 2023 17:02:35 +0100 Subject: [PATCH] dmaengine: dmatest: prevent using swiotlb buffer with nobounce parameter Source and destination data buffers are allocated with GPF_KERNEL flag. It means that, if the DDR is more than 2GB, buffers can be allocated above the 32-bit addressable space. In this case, and if the dma controller is only 32-bit compatible, swiotlb bounce buffer, located in the 32-bit addressable space, is used and introduces a memcpy. To prevent this extra memcpy, due to swiotlb bounce buffer use because source or destination data buffer is allocated above the 32-bit addressable space, force source and destination data buffers allocation with GPF_DMA instead, when nobounce parameter is true. Signed-off-by: Amelie Delaunay Link: https://lore.kernel.org/r/20231124160235.2459326-1-amelie.delaunay@foss.st.com Signed-off-by: Vinod Koul --- drivers/dma/dmatest.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c index ffe621695e47..a4f608837849 100644 --- a/drivers/dma/dmatest.c +++ b/drivers/dma/dmatest.c @@ -21,6 +21,10 @@ #include #include +static bool nobounce; +module_param(nobounce, bool, 0644); +MODULE_PARM_DESC(nobounce, "Prevent using swiotlb buffer (default: use swiotlb buffer)"); + static unsigned int test_buf_size = 16384; module_param(test_buf_size, uint, 0644); MODULE_PARM_DESC(test_buf_size, "Size of the memcpy test buffer"); @@ -90,6 +94,7 @@ MODULE_PARM_DESC(polled, "Use polling for completion instead of interrupts"); /** * struct dmatest_params - test parameters. + * @nobounce: prevent using swiotlb buffer * @buf_size: size of the memcpy test buffer * @channel: bus ID of the channel to test * @device: bus ID of the DMA Engine to test @@ -106,6 +111,7 @@ MODULE_PARM_DESC(polled, "Use polling for completion instead of interrupts"); * @polled: use polling for completion instead of interrupts */ struct dmatest_params { + bool nobounce; unsigned int buf_size; char channel[20]; char device[32]; @@ -215,6 +221,7 @@ struct dmatest_done { struct dmatest_data { u8 **raw; u8 **aligned; + gfp_t gfp_flags; unsigned int cnt; unsigned int off; }; @@ -533,7 +540,7 @@ static int dmatest_alloc_test_data(struct dmatest_data *d, goto err; for (i = 0; i < d->cnt; i++) { - d->raw[i] = kmalloc(buf_size + align, GFP_KERNEL); + d->raw[i] = kmalloc(buf_size + align, d->gfp_flags); if (!d->raw[i]) goto err; @@ -655,6 +662,13 @@ static int dmatest_func(void *data) goto err_free_coefs; } + src->gfp_flags = GFP_KERNEL; + dst->gfp_flags = GFP_KERNEL; + if (params->nobounce) { + src->gfp_flags = GFP_DMA; + dst->gfp_flags = GFP_DMA; + } + if (dmatest_alloc_test_data(src, buf_size, align) < 0) goto err_free_coefs; @@ -1093,6 +1107,7 @@ static void add_threaded_test(struct dmatest_info *info) struct dmatest_params *params = &info->params; /* Copy test parameters */ + params->nobounce = nobounce; params->buf_size = test_buf_size; strscpy(params->channel, strim(test_channel), sizeof(params->channel)); strscpy(params->device, strim(test_device), sizeof(params->device));