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   1 wifi: ath11k: Fix DMA buffer allocation to resolve SWIOTLB issues
   2 Currently, the driver allocates cacheable DMA buffers for rings like
   3 HAL_REO_DST and HAL_WBM2SW_RELEASE. The buffers for HAL_WBM2SW_RELEASE
   4 are large (1024 KiB), exceeding the SWIOTLB slot size of 256 KiB. This
   5 leads to "swiotlb buffer is full" error messages on systems without an
   6 IOMMU that use SWIOTLB, causing driver initialization failures. The driver
   7 calls dma_map_single() with these large buffers obtained from kzalloc(),
   8 resulting in ring initialization errors on systems without an IOMMU that
   9 use SWIOTLB.
  10
  11 To address these issues, replace the flawed buffer allocation mechanism
  12 with the appropriate DMA API. Specifically, use dma_alloc_noncoherent()
  13 for cacheable DMA buffers, ensuring proper freeing of buffers with
  14 dma_free_noncoherent().
  15
  16 Error log:
  17 [   10.194343] ath11k_pci 0000:04:00.0: swiotlb buffer is full (sz:1048583 bytes), total 32768 (slots), used 2529 (slots)
  18 [   10.194406] ath11k_pci 0000:04:00.0: failed to set up tcl_comp ring (0) :-12
  19 [   10.194781] ath11k_pci 0000:04:00.0: failed to init DP: -12
  20
  21 Tested-on: QCN9074 hw1.0 PCI WLAN.HK.2.7.0.1-01744-QCAHKSWPL_SILICONZ-1
  22 Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3
  23
  24 Reported-by: Tim Harvey <tharvey@gateworks.com>
  25 Closes: https://lore.kernel.org/all/20241210041133.GA17116@lst.de/
  26 Signed-off-by: P Praneesh <quic_ppranees@quicinc.com>
  27 Tested-by: Tim Harvey <tharvey@gateworks.com>
  28 Link: https://patch.msgid.link/20250119164219.647059-2-quic_ppranees@quicinc.com
  29 Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>
  30 --- a/drivers/net/wireless/ath/ath11k/dp.c
  31 +++ b/drivers/net/wireless/ath/ath11k/dp.c
  32 @@ -1,7 +1,7 @@
  33  // SPDX-License-Identifier: BSD-3-Clause-Clear
  34  /*
  35   * Copyright (c) 2018-2019 The Linux Foundation. All rights reserved.
  36 - * Copyright (c) 2021-2024 Qualcomm Innovation Center, Inc. All rights reserved.
  37 + * Copyright (c) 2021-2025 Qualcomm Innovation Center, Inc. All rights reserved.
  38   */
  39
  40  #include <crypto/hash.h>
  41 @@ -104,14 +104,12 @@ void ath11k_dp_srng_cleanup(struct ath11
  42         if (!ring->vaddr_unaligned)
  43                 return;
  44
  45 -       if (ring->cached) {
  46 -               dma_unmap_single(ab->dev, ring->paddr_unaligned, ring->size,
  47 -                                DMA_FROM_DEVICE);
  48 -               kfree(ring->vaddr_unaligned);
  49 -       } else {
  50 +       if (ring->cached)
  51 +               dma_free_noncoherent(ab->dev, ring->size, ring->vaddr_unaligned,
  52 +                                    ring->paddr_unaligned, DMA_FROM_DEVICE);
  53 +       else
  54                 dma_free_coherent(ab->dev, ring->size, ring->vaddr_unaligned,
  55                                   ring->paddr_unaligned);
  56 -       }
  57
  58         ring->vaddr_unaligned = NULL;
  59  }
  60 @@ -249,25 +247,14 @@ int ath11k_dp_srng_setup(struct ath11k_b
  61                 default:
  62                         cached = false;
  63                 }
  64 -
  65 -               if (cached) {
  66 -                       ring->vaddr_unaligned = kzalloc(ring->size, GFP_KERNEL);
  67 -                       if (!ring->vaddr_unaligned)
  68 -                               return -ENOMEM;
  69 -
  70 -                       ring->paddr_unaligned = dma_map_single(ab->dev,
  71 -                                                              ring->vaddr_unaligned,
  72 -                                                              ring->size,
  73 -                                                              DMA_FROM_DEVICE);
  74 -                       if (dma_mapping_error(ab->dev, ring->paddr_unaligned)) {
  75 -                               kfree(ring->vaddr_unaligned);
  76 -                               ring->vaddr_unaligned = NULL;
  77 -                               return -ENOMEM;
  78 -                       }
  79 -               }
  80         }
  81
  82 -       if (!cached)
  83 +       if (cached)
  84 +               ring->vaddr_unaligned = dma_alloc_noncoherent(ab->dev, ring->size,
  85 +                                                             &ring->paddr_unaligned,
  86 +                                                             DMA_FROM_DEVICE,
  87 +                                                             GFP_KERNEL);
  88 +       else
  89                 ring->vaddr_unaligned = dma_alloc_coherent(ab->dev, ring->size,
  90                                                            &ring->paddr_unaligned,
  91                                                            GFP_KERNEL);