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    SubjectRe: [PATCH 15/25] dmaengine: dw-edma: Convert DebugFS descs to being kz-allocated
    On Thu, Mar 24, 2022 at 04:48:26AM +0300, Serge Semin wrote:
    > Currently all the DW eDMA DebugFS nodes descriptors are allocated on
    > stack, while the DW eDMA driver private data and CSR limits are statically
    > preserved. Such design won't work for the multi-eDMA platforms.

    Can you please explain why?

    > As a
    > preparation to adding the multi-eDMA system setups support we need to have
    > each DebugFS node separately allocated and described. Afterwards we'll put
    > an addition info there like Read/Write channel flag, channel ID, DW eDMA
    > private data reference.
    >
    > Note this conversion is mainly required due to having the legacy DW eDMA
    > controllers with indirect Read/Write channels context CSRs access. If we
    > didn't need to have a synchronized access to these registers the DebugFS
    > code of the driver would have been much simpler.
    >

    I fail to understand how this change is beneficial or the exact issue.

    > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
    > ---
    > drivers/dma/dw-edma/dw-edma-v0-debugfs.c | 15 ++++++++++++---
    > 1 file changed, 12 insertions(+), 3 deletions(-)
    >
    > diff --git a/drivers/dma/dw-edma/dw-edma-v0-debugfs.c b/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
    > index afd519d9568b..7eb0147912fa 100644
    > --- a/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
    > +++ b/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
    > @@ -53,7 +53,8 @@ struct dw_edma_debugfs_entry {
    >
    > static int dw_edma_debugfs_u32_get(void *data, u64 *val)
    > {
    > - void __iomem *reg = data;
    > + struct dw_edma_debugfs_entry __iomem *entry = data;

    Why the entry has to be of __iomem?

    Thanks,
    Mani

    > + void __iomem *reg = entry->reg;
    >
    > if (dw->chip->mf == EDMA_MF_EDMA_LEGACY &&
    > reg >= (void __iomem *)&regs->type.legacy.ch) {
    > @@ -94,14 +95,22 @@ static int dw_edma_debugfs_u32_get(void *data, u64 *val)
    > }
    > DEFINE_DEBUGFS_ATTRIBUTE(fops_x32, dw_edma_debugfs_u32_get, NULL, "0x%08llx\n");
    >
    > -static void dw_edma_debugfs_create_x32(const struct dw_edma_debugfs_entry entries[],
    > +static void dw_edma_debugfs_create_x32(const struct dw_edma_debugfs_entry ini[],
    > int nr_entries, struct dentry *dir)
    > {
    > + struct dw_edma_debugfs_entry *entries;
    > int i;
    >
    > + entries = devm_kcalloc(dw->chip->dev, nr_entries, sizeof(*entries),
    > + GFP_KERNEL);
    > + if (!entries)
    > + return;
    > +
    > for (i = 0; i < nr_entries; i++) {
    > + entries[i] = ini[i];
    > +
    > debugfs_create_file_unsafe(entries[i].name, 0444, dir,
    > - entries[i].reg, &fops_x32);
    > + &entries[i], &fops_x32);
    > }
    > }
    >
    > --
    > 2.35.1
    >

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