ipq806x: do not allocate coherent memory in dma engine hotpath

The available amount of coherent DMA memory is very limited. On Linux
4.4 this issue was worked around by increasing the pool size.

It turns out that using coherent memory here is completely unnecessary.
This change reworks the driver code to use kzalloc+dma_map_single
instead.

Signed-off-by: Felix Fietkau <[email protected]>

diff --git a/target/linux/ipq806x/patches-4.9/0002-dmaengine-Add-ADM-driver.patch b/target/linux/ipq806x/patches-4.9/0002-dmaengine-Add-ADM-driver.patch
index 212a90290526a3179c9d3dac6afd58cbe68b18f3..4ad025c9c7fb0dad64609dc788dbee4b3b6044fd 100644 (file)
--- a/target/linux/ipq806x/patches-4.9/0002-dmaengine-Add-ADM-driver.patch
+++ b/target/linux/ipq806x/patches-4.9/0002-dmaengine-Add-ADM-driver.patch
@@ -49,7 +49,7 @@ Signed-off-by: Thomas Pedersen <[email protected]>
 +obj-$(CONFIG_QCOM_ADM) += qcom_adm.o
 --- /dev/null
 +++ b/drivers/dma/qcom/qcom_adm.c
-@@ -0,0 +1,900 @@
+@@ -0,0 +1,914 @@
 +/*
 + * Copyright (c) 2013-2015, The Linux Foundation. All rights reserved.
 + *
@@ -406,6 +406,7 @@ Signed-off-by: Thomas Pedersen <[email protected]>
 +      struct adm_device *adev = achan->adev;
 +      struct adm_async_desc *async_desc;
 +      struct scatterlist *sg;
++      dma_addr_t cple_addr;
 +      u32 i, burst;
 +      u32 single_count = 0, box_count = 0, crci = 0;
 +      void *desc;
@@ -454,7 +455,7 @@ Signed-off-by: Thomas Pedersen <[email protected]>
 +              }
 +      }
 +
-+      async_desc = kzalloc(sizeof(*async_desc), GFP_NOWAIT);
++      async_desc = kzalloc(sizeof(*async_desc), GFP_ATOMIC);
 +      if (!async_desc)
 +              return ERR_PTR(-ENOMEM);
 +
@@ -467,13 +468,9 @@ Signed-off-by: Thomas Pedersen <[email protected]>
 +                              box_count * sizeof(struct adm_desc_hw_box) +
 +                              sizeof(*cple) + 2 * ADM_DESC_ALIGN;
 +
-+      async_desc->cpl = dma_alloc_writecombine(adev->dev, async_desc->dma_len,
-+                              &async_desc->dma_addr, GFP_NOWAIT);
-+
-+      if (!async_desc->cpl) {
-+              kfree(async_desc);
-+              return ERR_PTR(-ENOMEM);
-+      }
++      async_desc->cpl = kzalloc(async_desc->dma_len, GFP_ATOMIC);
++      if (!async_desc->cpl)
++              goto free;
 +
 +      async_desc->adev = adev;
 +
@@ -481,10 +478,6 @@ Signed-off-by: Thomas Pedersen <[email protected]>
 +      cple = PTR_ALIGN(async_desc->cpl, ADM_DESC_ALIGN);
 +      desc = PTR_ALIGN(cple + 1, ADM_DESC_ALIGN);
 +
-+      /* init cmd list */
-+      *cple = ADM_CPLE_LP;
-+      *cple |= (desc - async_desc->cpl + async_desc->dma_addr) >> 3;
-+
 +      for_each_sg(sgl, sg, sg_len, i) {
 +              async_desc->length += sg_dma_len(sg);
 +
@@ -496,7 +489,27 @@ Signed-off-by: Thomas Pedersen <[email protected]>
 +                                                         direction);
 +      }
 +
++      async_desc->dma_addr = dma_map_single(adev->dev, async_desc->cpl,
++                                            async_desc->dma_len,
++                                            DMA_TO_DEVICE);
++      if (dma_mapping_error(adev->dev, async_desc->dma_addr))
++              goto free;
++
++      cple_addr = async_desc->dma_addr + ((void *)cple - async_desc->cpl);
++
++      /* init cmd list */
++      dma_sync_single_for_cpu(adev->dev, cple_addr, sizeof(*cple),
++                              DMA_TO_DEVICE);
++      *cple = ADM_CPLE_LP;
++      *cple |= (async_desc->dma_addr + ADM_DESC_ALIGN) >> 3;
++      dma_sync_single_for_device(adev->dev, cple_addr, sizeof(*cple),
++                                 DMA_TO_DEVICE);
++
 +      return vchan_tx_prep(&achan->vc, &async_desc->vd, flags);
++
++free:
++      kfree(async_desc);
++      return ERR_PTR(-ENOMEM);
 +}
 +
 +/**
@@ -721,8 +734,9 @@ Signed-off-by: Thomas Pedersen <[email protected]>
 +      struct adm_async_desc *async_desc = container_of(vd,
 +                      struct adm_async_desc, vd);
 +
-+      dma_free_writecombine(async_desc->adev->dev, async_desc->dma_len,
-+              async_desc->cpl, async_desc->dma_addr);
++      dma_unmap_single(async_desc->adev->dev, async_desc->dma_addr,
++                       async_desc->dma_len, DMA_TO_DEVICE);
++      kfree(async_desc->cpl);
 +      kfree(async_desc);
 +}
 +