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Message-ID: <20090429182450.GA9057@elte.hu>
Date: Wed, 29 Apr 2009 20:24:50 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Borislav Petkov <borislav.petkov@....com>
Cc: akpm@...ux-foundation.org, greg@...ah.com, tglx@...utronix.de,
hpa@...or.com, dougthompson@...ssion.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 13/21] amd64_edac: add f10-and-later methods-p3
* Ingo Molnar <mingo@...e.hu> wrote:
>
> * Borislav Petkov <borislav.petkov@....com> wrote:
>
> > From: Doug Thompson <dougthompson@...ssion.com>
> >
> > Signed-off-by: Doug Thompson <dougthompson@...ssion.com>
> > Signed-off-by: Borislav Petkov <borislav.petkov@....com>
> > ---
> > drivers/edac/amd64_edac.c | 318 +++++++++++++++++++++++++++++++++++++++++++++
> > 1 files changed, 318 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
> > index fe2342c..84075c0 100644
> > --- a/drivers/edac/amd64_edac.c
> > +++ b/drivers/edac/amd64_edac.c
> > @@ -2726,4 +2726,322 @@ static int f10_lookup_addr_in_dct(u32 InputAddr, u32 NodeID, u32 ChannelSelect)
> > return CSFound;
> > }
> >
> > +/*
> > + * f10_match_to_this_node
> > + *
> > + * For a given 'DramRange' value, check if 'SystemAddr' fall within this value
> > + */
> > +static int f10_match_to_this_node(struct amd64_pvt *pvt, int DramRange,
> > + u64 SystemAddr,
> > + int *node_id,
> > + int *channel_select)
> > +{
> > + int CSFound = -1;
> > + int NodeID;
> > + int HiRangeSelected;
> > + u32 IntlvEn, IntlvSel;
> > + u32 DramEn;
> > + u32 Ilog;
> > + u32 HoleOffset, HoleEn;
> > + u32 InputAddr, Temp;
> > + u32 DctSelBaseAddr, DctSelIntLvAddr;
> > + u32 DctSelHi;
> > + u32 ChannelSelect;
> > + u64 DramBaseLong, DramLimitLong;
> > + u64 DctSelBaseOffsetLong, ChannelAddrLong;
> > +
> > + /* DRAM Base value for this DRAM instance */
> > + DramBaseLong = pvt->dram_base[DramRange];
> > + DramEn = pvt->dram_rw_en[DramRange];
> > + IntlvEn = pvt->dram_IntlvEn[DramRange];
> > +
> > + /* DRAM Limit value for this DRAM instance */
> > + DramLimitLong = pvt->dram_limit[DramRange];
> > + NodeID = pvt->dram_DstNode[DramRange];
> > + IntlvSel = pvt->dram_IntlvSel[DramRange];
> > +
> > + debugf1("%s(dram=%d) Base=0x%llx SystemAddr= 0x%llx Limit=0x%llx\n",
> > + __func__, DramRange, DramBaseLong, SystemAddr, DramLimitLong);
> > +
> > + /* This assumes that one node's DHAR is the same as
> > + * all the other node's DHARs
> > + */
> > + HoleEn = pvt->dhar;
> > + HoleOffset = (HoleEn & 0x0000FF80);
> > + HoleEn = (HoleEn & 0x00000003);
> > +
> > + debugf1(" HoleOffset=0x%x HoleEn=0x%x IntlvSel=0x%x\n",
> > + HoleOffset, HoleEn, IntlvSel);
> > +
> > + if ((IntlvEn == 0) || IntlvSel == ((SystemAddr >> 12) & IntlvEn)) {
> > +
> > + Ilog = f10_map_IntlvEn_to_shift(IntlvEn);
> > +
> > + Temp = pvt->dram_ctl_select_low;
> > + DctSelBaseOffsetLong = pvt->dram_ctl_select_high << 16;
> > +
> > + DctSelHi = (Temp >> 1) & 1;
> > + DctSelIntLvAddr = dct_sel_interleave_addr(pvt);
> > + DctSelBaseAddr = dct_sel_baseaddr(pvt);
> > +
> > + if (dct_high_range_enabled(pvt) &&
> > + !dct_ganging_enabled(pvt) &&
> > + ((SystemAddr >> 27) >= (DctSelBaseAddr >> 11)))
> > + HiRangeSelected = 1;
> > + else
> > + HiRangeSelected = 0;
> > +
> > + ChannelSelect = f10_determine_channel(pvt, SystemAddr,
> > + HiRangeSelected, IntlvEn);
> > +
> > + ChannelAddrLong = f10_determine_base_addr_offset(
> > + SystemAddr,
> > + HiRangeSelected,
> > + DctSelBaseAddr,
> > + DctSelBaseOffsetLong,
> > + HoleEn,
> > + HoleOffset,
> > + DramBaseLong);
> > +
> > + /* Remove Node ID (in case of processor interleaving) */
> > + Temp = ChannelAddrLong & 0xFC0;
> > +
> > + ChannelAddrLong = ((ChannelAddrLong >> Ilog) &
> > + 0xFFFFFFFFF000ULL) | Temp;
> > +
> > + /* Remove Channel interleave and hash */
> > + if (dct_interleave_enabled(pvt) &&
> > + !dct_high_range_enabled(pvt) &&
> > + !dct_ganging_enabled(pvt)) {
> > + if (DctSelIntLvAddr != 1)
> > + ChannelAddrLong =
> > + (ChannelAddrLong >> 1) &
> > + 0xFFFFFFFFFFFFFFC0ULL;
> > + else {
> > + Temp = ChannelAddrLong & 0xFC0;
> > + ChannelAddrLong =
> > + ((ChannelAddrLong &
> > + 0xFFFFFFFFFFFFC000ULL)
> > + >> 1) | Temp;
> > + }
> > + }
> > +
> > + /* Form a normalize InputAddr (Move bits 36:8 down to 28:0
> > + * which will set it up to match the DCT Base register
> > + */
> > + InputAddr = ChannelAddrLong >> 8;
> > +
> > + debugf1(" (ChannelAddrLong=0x%llx) >> 8 becomes "
> > + "InputAddr=0x%x\n", ChannelAddrLong, InputAddr);
> > +
> > + /* Iterate over the DRAM DCTs looking for a
> > + * match for InputAddr on the selected NodeID
> > + */
> > + CSFound = f10_lookup_addr_in_dct(InputAddr,
> > + NodeID, ChannelSelect);
> > +
> > + if (CSFound >= 0) {
> > + *node_id = NodeID;
> > + *channel_select = ChannelSelect;
> > + }
> > + }
> > +
> > + return CSFound;
> > +}
>
> this function is probably too large, and also it uses some weird
> hungarian notation coding style. Please dont do that! It's
> completely unacceptable.
>
> this condition:
>
> > + if ((IntlvEn == 0) || IntlvSel == ((SystemAddr >> 12) & IntlvEn)) {
>
> could be inverted and an early "return cs_found" could be done -
> saving an indentitation level for most of the above code.
>
> etc. etc.
>
> Please look at the function in a really large xterm, from far
> away. If the shape does not look 'good', and the structure is not
> an obvious pattern seen a hundred times elsewhere in the kernel,
> there's something weird going on with the function. It should be
> split up, cleaned up, simplified. Variable names could become
> shorter, etc. etc.
... and this general observation about variable naming and general
structure holds for the rest of the patches as well. This really
needs to be sorted out before a more detailed review can be done.
Ingo
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