[PATCH v5 1/7] riscv: Add DMA 64-bit address support

[Padmarao Begari]

Hi Bin,

On Fri, Dec 11, 2020 at 1:22 PM Bin Meng <bmeng.cn at gmail.com> wrote:

> Hi Padmarao,
>
> On Fri, Dec 11, 2020 at 3:10 PM Padmarao Begari <padmarao.b at gmail.com>
> wrote:
> >
> > Hi Bin,
> >
> > On Thu, Dec 10, 2020 at 4:11 PM Bin Meng <bmeng.cn at gmail.com> wrote:
> >>
> >> Hi Padmarao,
> >>
> >> On Thu, Dec 3, 2020 at 4:43 AM Padmarao Begari
> >> <padmarao.begari at microchip.com> wrote:
> >> >
> >> > dma_addr_t holds any valid DMA address. If the DMA API only uses
> 32/64-bit
> >> > addresses, dma_addr_t need only be 32/64 bits wide.
> >> >
> >> > Signed-off-by: Padmarao Begari <padmarao.begari at microchip.com>
> >> > Reviewed-by: Anup Patel <anup.patel at wdc.com>
> >> > ---
> >> >  arch/riscv/Kconfig             | 4 ++++
> >> >  arch/riscv/include/asm/types.h | 4 ++++
> >> >  2 files changed, 8 insertions(+)
> >> >
> >> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> >> > index 30b05408b1..55eaee2da6 100644
> >> > --- a/arch/riscv/Kconfig
> >> > +++ b/arch/riscv/Kconfig
> >> > @@ -152,6 +152,10 @@ config 32BIT
> >> >  config 64BIT
> >> >         bool
> >> >
> >> > +config DMA_ADDR_T_64BIT
> >> > +       bool
> >> > +       default y if 64BIT
> >> > +
> >> >  config SIFIVE_CLINT
> >> >         bool
> >> >         depends on RISCV_MMODE || SPL_RISCV_MMODE
> >> > diff --git a/arch/riscv/include/asm/types.h
> b/arch/riscv/include/asm/types.h
> >> > index 403cf9a48f..b800b2d221 100644
> >> > --- a/arch/riscv/include/asm/types.h
> >> > +++ b/arch/riscv/include/asm/types.h
> >> > @@ -29,7 +29,11 @@ typedef unsigned short umode_t;
> >> >
> >> >  #include <stddef.h>
> >> >
> >> > +#ifdef CONFIG_DMA_ADDR_T_64BIT
> >> > +typedef u64 dma_addr_t;
> >> > +#else
> >> >  typedef u32 dma_addr_t;
> >> > +#endif
> >>
> >> Why is this patch needed for U-Boot?
> >>
> >
> > Initially this patch was created for the MACB driver dependency and now
> the MACB driver is not dependent on CONFIG_DMA_ADDR_T_64BIT.
> > But We created this patch the same as the ARM 64-bit kconfig and the
> 'CONFIG_DMA_ADDR_T_64BIT' is used when the MMC driver is configured with
> DMA.
> >
>
> But in U-Boot there is no 64-bit address. The DMA address should be
> under 4G. Both MACB and MMC driver should work with the 32-bit DMA
> addresses, no?
>
>
We will use 64-bit addresses in the future.
Both MACB and MMC drivers work with 64-bit DMA addresses in the PolarFire
SoC.

Regards
Padmarao



> Regards,
> Bin
>