Re: [PATCH v3 5/6] dmaengine: dw-edma: add flags at struct dw_edma_chip

[Zhi Li <lznuaa@gmail.com>]

On Thu, Mar 10, 2022 at 1:44 AM Manivannan Sadhasivam
<manivannan.sadhasivam@linaro.org> wrote:
>
> On Mon, Mar 07, 2022 at 04:47:49PM -0600, Frank Li wrote:
> > Allow PCI EP probe DMA locally and prevent use of remote MSI
> > to remote PCI host.
> >
> > Add option to force 32bit DBI register access even on
> > 64-bit systems. i.MX8 hardware only allowed 32bit register
> > access.
> >
> > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > ---
> >
> > Resend added dmaengine@vger.kernel.org
> >
> > Change from v2 to v3
> >  - rework commit message
> >  - Change to DW_EDMA_CHIP_32BIT_DBI
> >  - using DW_EDMA_CHIP_LOCAL control msi
> >  - Apply Bjorn's comments,
> >       if (!j) {
> >                control |= DW_EDMA_V0_LIE;
> >                if (!(chan->chip->flags & DW_EDMA_CHIP_LOCAL))
> >                                control |= DW_EDMA_V0_RIE;
> >         }
> >
> >       if ((chan->chip->flags & DW_EDMA_CHIP_REG32BIT) ||
> >               !IS_ENABLED(CONFIG_64BIT)) {
> >           SET_CH_32(...);
> >           SET_CH_32(...);
> >        } else {
> >           SET_CH_64(...);
> >        }
> >
> >
> > Change from v1 to v2
> > - none
> >
> >  drivers/dma/dw-edma/dw-edma-v0-core.c | 20 ++++++++++++--------
> >  include/linux/dma/edma.h              |  9 +++++++++
> >  2 files changed, 21 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/dma/dw-edma/dw-edma-v0-core.c b/drivers/dma/dw-edma/dw-edma-v0-core.c
> > index 6e2f83e31a03a..081cd7997348d 100644
> > --- a/drivers/dma/dw-edma/dw-edma-v0-core.c
> > +++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
> > @@ -307,6 +307,7 @@ u32 dw_edma_v0_core_status_abort_int(struct dw_edma_chip *chip, enum dw_edma_dir
> >  static void dw_edma_v0_core_write_chunk(struct dw_edma_chunk *chunk)
> >  {
> >       struct dw_edma_burst *child;
> > +     struct dw_edma_chan *chan = chunk->chan;
> >       struct dw_edma_v0_lli __iomem *lli;
> >       struct dw_edma_v0_llp __iomem *llp;
> >       u32 control = 0, i = 0;
> > @@ -320,9 +321,11 @@ static void dw_edma_v0_core_write_chunk(struct dw_edma_chunk *chunk)
> >       j = chunk->bursts_alloc;
> >       list_for_each_entry(child, &chunk->burst->list, list) {
> >               j--;
> > -             if (!j)
> > -                     control |= (DW_EDMA_V0_LIE | DW_EDMA_V0_RIE);
> > -
> > +             if (!j) {
> > +                     control |= DW_EDMA_V0_LIE;
> > +                     if (!(chan->chip->flags & DW_EDMA_CHIP_LOCAL))
> > +                             control |= DW_EDMA_V0_RIE;
> > +             }
> >               /* Channel control */
> >               SET_LL_32(&lli[i].control, control);
> >               /* Transfer size */
> > @@ -420,15 +423,16 @@ void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
> >               SET_CH_32(chip, chan->dir, chan->id, ch_control1,
> >                         (DW_EDMA_V0_CCS | DW_EDMA_V0_LLE));
> >               /* Linked list */
> > -             #ifdef CONFIG_64BIT
> > -                     SET_CH_64(chip, chan->dir, chan->id, llp.reg,
> > -                               chunk->ll_region.paddr);
> > -             #else /* CONFIG_64BIT */
> > +             if ((chan->chip->flags & DW_EDMA_CHIP_32BIT_DBI) ||
> > +                 !IS_ENABLED(CONFIG_64BIT)) {
> >                       SET_CH_32(chip, chan->dir, chan->id, llp.lsb,
> >                                 lower_32_bits(chunk->ll_region.paddr));
> >                       SET_CH_32(chip, chan->dir, chan->id, llp.msb,
> >                                 upper_32_bits(chunk->ll_region.paddr));
> > -             #endif /* CONFIG_64BIT */
> > +             } else {
> > +                     SET_CH_64(chip, chan->dir, chan->id, llp.reg,
> > +                               chunk->ll_region.paddr);
> > +             }
> >       }
> >       /* Doorbell */
> >       SET_RW_32(chip, chan->dir, doorbell,
> > diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
> > index fcfbc0f47f83d..4321f6378ef66 100644
> > --- a/include/linux/dma/edma.h
> > +++ b/include/linux/dma/edma.h
> > @@ -33,6 +33,12 @@ enum dw_edma_map_format {
> >       EDMA_MF_HDMA_COMPAT = 0x5
> >  };
> >
> > +/* Probe EDMA engine locally and prevent generate MSI to host side*/
> > +#define DW_EDMA_CHIP_LOCAL   BIT(0)
> > +
> > +/* Only support 32bit DBI register access */
> > +#define DW_EDMA_CHIP_32BIT_DBI       BIT(1)
> > +
>
> How about using an enum for defining the flags? This would help us organize the
> flags in a more coherent way and also will give the benefit of kdoc.

Did you see other linux code use enum as bitmask?
According to my understanding, enum just chooses values in a list.

>
> /**
>  * enum dw_edma_chip_flags - Flags specific to an eDMA chip
>  * @DW_EDMA_CHIP_LOCAL:         eDMA is used locally by an endpoint
>  * @DW_EDMA_CHIP_32BIT_DBI:     eDMA only supports 32bit DBI access
>  */
> enum dw_edma_chip_flags {
>         DW_EDMA_CHIP_LOCAL = BIT(0),
>         DW_EDMA_CHIP_32BIT_DBI = BIT(1),
> };
>
> >  /**
> >   * struct dw_edma_chip - representation of DesignWare eDMA controller hardware
> >   * @dev:              struct device of the eDMA controller
> > @@ -40,6 +46,8 @@ enum dw_edma_map_format {
> >   * @nr_irqs:          total dma irq number
> >   * reg64bit           if support 64bit write to register
> >   * @ops                       DMA channel to IRQ number mapping
> > + * @flags             - DW_EDMA_CHIP_LOCAL
> > + *                    - DW_EDMA_CHIP_32BIT_DBI
>
> No need to mention the flags here if you use the enum I suggested above.
>
> >   * @wr_ch_cnt                 DMA write channel number
> >   * @rd_ch_cnt                 DMA read channel number
> >   * @rg_region                 DMA register region
> > @@ -53,6 +61,7 @@ struct dw_edma_chip {
> >       int                     id;
> >       int                     nr_irqs;
> >       const struct dw_edma_core_ops   *ops;
> > +     u32                     flags;
>
>         enum dw_edma_chip_flags flags;
>
> Thanks,
> Mani
>
> >
> >       void __iomem            *reg_base;
> >
> > --
> > 2.24.0.rc1
> >