Re: [PATCH net-next v3 09/12] net: stmmac: dwmac4: Allow platforms to specify some DMA/MTL offsets

Andrew Halaney
2023-04-07T17:37:01Z

On Sat, Apr 01, 2023 at 04:58:59PM +0200, Simon Horman wrote:
> On Fri, Mar 31, 2023 at 04:45:46PM -0500, Andrew Halaney wrote:
> > Some platforms have dwmac4 implementations that have a different
> > address space layout than the default, resulting in the need to define
> > their own DMA/MTL offsets.
> >
> > Extend the functions to allow a platform driver to indicate what its
> > addresses are, overriding the defaults.
> >
> > Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
> > ---
> >
> > This patch (and the prior patch) are replacements for
> > https://lore.kernel.org/netdev/20230320204153.21736840@kernel.org/
> > as was requested. Hopefully I was understanding the intent correctly :)
> >
> > I'm pretty sure further refinement will be requested for this one, but
> > it is the best I could come up with myself! Specifically some of the
> > naming, dealing with spacing in some older spots of dwmac4,
> > where the addresses should live in the structure hierarchy, etc are
> > things I would not be surprised to have to rework if this is still
> > preferred over the wrapper approach.
> >
> > Changes since v2:
> > * New, replacing old wrapper approach
> >
> > drivers/net/ethernet/stmicro/stmmac/dwmac4.h | 91 ++++++++--
> > .../net/ethernet/stmicro/stmmac/dwmac4_core.c | 36 ++--
> > .../net/ethernet/stmicro/stmmac/dwmac4_dma.c | 157 ++++++++++--------
> > .../net/ethernet/stmicro/stmmac/dwmac4_dma.h | 51 +++---
> > .../net/ethernet/stmicro/stmmac/dwmac4_lib.c | 67 +++++---
> > include/linux/stmmac.h | 19 +++
> > 6 files changed, 279 insertions(+), 142 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4.h b/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
> > index ccd49346d3b3..a0c0ee1dc13f 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
> > +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
> > @@ -336,14 +336,23 @@ enum power_event {
> >
> > #define MTL_CHAN_BASE_ADDR 0x00000d00
> > #define MTL_CHAN_BASE_OFFSET 0x40
> > -#define MTL_CHANX_BASE_ADDR(x) (MTL_CHAN_BASE_ADDR + \
> > - (x * MTL_CHAN_BASE_OFFSET))
> > -
> > -#define MTL_CHAN_TX_OP_MODE(x) MTL_CHANX_BASE_ADDR(x)
> > -#define MTL_CHAN_TX_DEBUG(x) (MTL_CHANX_BASE_ADDR(x) + 0x8)
> > -#define MTL_CHAN_INT_CTRL(x) (MTL_CHANX_BASE_ADDR(x) + 0x2c)
> > -#define MTL_CHAN_RX_OP_MODE(x) (MTL_CHANX_BASE_ADDR(x) + 0x30)
> > -#define MTL_CHAN_RX_DEBUG(x) (MTL_CHANX_BASE_ADDR(x) + 0x38)
> > +#define MTL_CHANX_BASE_ADDR(addrs, x) \
> > +({ \
> > + const struct dwmac4_addrs *__addrs = addrs; \
> > + const u32 __x = x; \
> > + u32 __addr; \
> > + if (__addrs) \
> > + __addr = __addrs->mtl_chan + (__x * __addrs->mtl_chan_offset); \
> > + else \
> > + __addr = MTL_CHAN_BASE_ADDR + (__x * MTL_CHAN_BASE_OFFSET); \
> > + __addr; \
> > +})
>
> Could this and similar macros added by this patch be functions?
> From my pov a benefit would be slightly more type safety.
> And as a bonus there wouldn't be any need to handle aliasing of input.
>

Sure, to be honest I'll be much more comfortable coding that up anyways.
I don't do a ton of macro programming and had to refamiliarize myself of
the pitfalls that comes with it when doing this.

Thanks,
Andrew