lkml.org 
[lkml]   [2023]   [Jan]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v9 06/27] dmaengine: dw-edma: Fix invalid interleaved xfers semantics
    Date
    The interleaved DMA transfer support added in commit 85e7518f42c8
    ("dmaengine: dw-edma: Add device_prep_interleave_dma() support") seems
    contradicting to what the DMA-engine defines. The next conditional
    statements:
    if (!xfer->xfer.il->numf)
    return NULL;
    if (xfer->xfer.il->numf > 0 && xfer->xfer.il->frame_size > 0)
    return NULL;
    basically mean that numf can't be zero and frame_size must always be zero,
    otherwise the transfer won't be executed. But further the transfer
    execution method takes the frames size from the
    dma_interleaved_template.sgl[] array for each frame. That array in
    accordance with [1] is supposed to be of
    dma_interleaved_template.frame_size size, which as we discovered before
    the code expects to be zero. So judging by the dw_edma_device_transfer()
    implementation the method implies the dma_interleaved_template.sgl[] array
    being of dma_interleaved_template.numf size, which is wrong. Since the
    dw_edma_device_transfer() method doesn't permit
    dma_interleaved_template.frame_size being non-zero then actual multi-chunk
    interleaved transfer turns to be unsupported even though the code implies
    having it supported.

    Let's fix that by adding a fully functioning support of the interleaved
    DMA transfers. First of all dma_interleaved_template.frame_size is
    supposed to be greater or equal to one thus having at least simple linear
    chunked frames. Secondly we can create a walk-through all over the chunks
    and frames just by initializing the number of the eDMA burst transactios
    as a multiple of dma_interleaved_template.numf and
    dma_interleaved_template.frame_size and getting the frame_size-modulo of
    the iteration step as an index of the dma_interleaved_template.sgl[]
    array. The rest of the dw_edma_device_transfer() method code can be left
    unchanged.

    [1] include/linux/dmaengine.h: doc struct dma_interleaved_template

    Fixes: 85e7518f42c8 ("dmaengine: dw-edma: Add device_prep_interleave_dma() support")
    Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
    Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
    Tested-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
    Acked-by: Vinod Koul <vkoul@kernel.org>
    ---
    drivers/dma/dw-edma/dw-edma-core.c | 18 +++++++-----------
    1 file changed, 7 insertions(+), 11 deletions(-)

    diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
    index 35588e14f79a..d5c4192141ef 100644
    --- a/drivers/dma/dw-edma/dw-edma-core.c
    +++ b/drivers/dma/dw-edma/dw-edma-core.c
    @@ -332,6 +332,7 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer)
    struct dw_edma_chunk *chunk;
    struct dw_edma_burst *burst;
    struct dw_edma_desc *desc;
    + size_t fsz = 0;
    u32 cnt = 0;
    int i;

    @@ -381,9 +382,7 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer)
    if (xfer->xfer.sg.len < 1)
    return NULL;
    } else if (xfer->type == EDMA_XFER_INTERLEAVED) {
    - if (!xfer->xfer.il->numf)
    - return NULL;
    - if (xfer->xfer.il->numf > 0 && xfer->xfer.il->frame_size > 0)
    + if (!xfer->xfer.il->numf || xfer->xfer.il->frame_size < 1)
    return NULL;
    if (!xfer->xfer.il->src_inc || !xfer->xfer.il->dst_inc)
    return NULL;
    @@ -413,10 +412,8 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer)
    cnt = xfer->xfer.sg.len;
    sg = xfer->xfer.sg.sgl;
    } else if (xfer->type == EDMA_XFER_INTERLEAVED) {
    - if (xfer->xfer.il->numf > 0)
    - cnt = xfer->xfer.il->numf;
    - else
    - cnt = xfer->xfer.il->frame_size;
    + cnt = xfer->xfer.il->numf * xfer->xfer.il->frame_size;
    + fsz = xfer->xfer.il->frame_size;
    }

    for (i = 0; i < cnt; i++) {
    @@ -438,7 +435,7 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer)
    else if (xfer->type == EDMA_XFER_SCATTER_GATHER)
    burst->sz = sg_dma_len(sg);
    else if (xfer->type == EDMA_XFER_INTERLEAVED)
    - burst->sz = xfer->xfer.il->sgl[i].size;
    + burst->sz = xfer->xfer.il->sgl[i % fsz].size;

    chunk->ll_region.sz += burst->sz;
    desc->alloc_sz += burst->sz;
    @@ -481,10 +478,9 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer)

    if (xfer->type == EDMA_XFER_SCATTER_GATHER) {
    sg = sg_next(sg);
    - } else if (xfer->type == EDMA_XFER_INTERLEAVED &&
    - xfer->xfer.il->frame_size > 0) {
    + } else if (xfer->type == EDMA_XFER_INTERLEAVED) {
    struct dma_interleaved_template *il = xfer->xfer.il;
    - struct data_chunk *dc = &il->sgl[i];
    + struct data_chunk *dc = &il->sgl[i % fsz];

    src_addr += burst->sz;
    if (il->src_sgl)
    --
    2.39.0

    \
     
     \ /
      Last update: 2023-03-26 23:41    [W:7.528 / U:1.344 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site