linux-kernel - Re: [PATCH] hwmon: (dimmtemp) Support more than 32 DIMMs

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Message-ID: <CABqG17ikQ4p0cVxhgfAxXgfTT7Zm5JDrjebrEyfwc-9Eyx3puA@mail.gmail.com>
Date:   Mon, 17 Jul 2023 15:11:07 +0530
From:   Naresh Solanki <naresh.solanki@...ements.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     devicetree@...r.kernel.org, Jean Delvare <jdelvare@...e.com>,
        Iwona Winiarska <iwona.winiarska@...el.com>,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>
Subject: Re: [PATCH] hwmon: (dimmtemp) Support more than 32 DIMMs

Hi Guenter

On Sat, 15 Jul 2023 at 22:28, Guenter Roeck <linux@...ck-us.net> wrote:
>
> On Tue, Jul 11, 2023 at 05:21:43PM +0200, Naresh Solanki wrote:
> > From: Patrick Rudolph <patrick.rudolph@...ements.com>
> >
> > This patch introduces support for handling more than 32 DIMMs by
> > utilizing bitmap operations. The changes ensure that the driver can
> > handle a higher number of DIMMs efficiently.
> >
> > Signed-off-by: Patrick Rudolph <patrick.rudolph@...ements.com>
>
> Applied to hwmon-next.
>
> Note: I got multiple versions of this patch. In the future
> please version your patches and provide change logs.
Sure thing. Thanks
~Naresh
>
> Thanks,
> Guenter
>
> > ---
> >  drivers/hwmon/peci/dimmtemp.c | 26 +++++++++++++++-----------
> >  1 file changed, 15 insertions(+), 11 deletions(-)
> >
> >
> > base-commit: 4dbbaf8fbdbd13adc80731b2452257857e4c2d8b
> >
> > diff --git a/drivers/hwmon/peci/dimmtemp.c b/drivers/hwmon/peci/dimmtemp.c
> > index ed968401f93c..ce89da3937a0 100644
> > --- a/drivers/hwmon/peci/dimmtemp.c
> > +++ b/drivers/hwmon/peci/dimmtemp.c
> > @@ -219,19 +219,21 @@ static int check_populated_dimms(struct peci_dimmtemp *priv)
> >  {
> >       int chan_rank_max = priv->gen_info->chan_rank_max;
> >       int dimm_idx_max = priv->gen_info->dimm_idx_max;
> > -     u32 chan_rank_empty = 0;
> > -     u32 dimm_mask = 0;
> > -     int chan_rank, dimm_idx, ret;
> > +     DECLARE_BITMAP(dimm_mask, DIMM_NUMS_MAX);
> > +     DECLARE_BITMAP(chan_rank_empty, CHAN_RANK_MAX);
> > +
> > +     int chan_rank, dimm_idx, ret, i;
> >       u32 pcs;
> >
> > -     BUILD_BUG_ON(BITS_PER_TYPE(chan_rank_empty) < CHAN_RANK_MAX);
> > -     BUILD_BUG_ON(BITS_PER_TYPE(dimm_mask) < DIMM_NUMS_MAX);
> >       if (chan_rank_max * dimm_idx_max > DIMM_NUMS_MAX) {
> >               WARN_ONCE(1, "Unsupported number of DIMMs - chan_rank_max: %d, dimm_idx_max: %d",
> >                         chan_rank_max, dimm_idx_max);
> >               return -EINVAL;
> >       }
> >
> > +     bitmap_zero(dimm_mask, DIMM_NUMS_MAX);
> > +     bitmap_zero(chan_rank_empty, CHAN_RANK_MAX);
> > +
> >       for (chan_rank = 0; chan_rank < chan_rank_max; chan_rank++) {
> >               ret = peci_pcs_read(priv->peci_dev, PECI_PCS_DDR_DIMM_TEMP, chan_rank, &pcs);
> >               if (ret) {
> > @@ -242,7 +244,7 @@ static int check_populated_dimms(struct peci_dimmtemp *priv)
> >                        * detection to be performed at a later point in time.
> >                        */
> >                       if (ret == -EINVAL) {
> > -                             chan_rank_empty |= BIT(chan_rank);
> > +                             bitmap_set(chan_rank_empty, chan_rank, 1);
> >                               continue;
> >                       }
> >
> > @@ -251,7 +253,7 @@ static int check_populated_dimms(struct peci_dimmtemp *priv)
> >
> >               for (dimm_idx = 0; dimm_idx < dimm_idx_max; dimm_idx++)
> >                       if (__dimm_temp(pcs, dimm_idx))
> > -                             dimm_mask |= BIT(chan_rank * dimm_idx_max + dimm_idx);
> > +                             bitmap_set(dimm_mask, chan_rank * dimm_idx_max + dimm_idx, 1);
> >       }
> >
> >       /*
> > @@ -260,7 +262,7 @@ static int check_populated_dimms(struct peci_dimmtemp *priv)
> >        * host platform boot. Retrying a couple of times lets us make sure
> >        * that the state is persistent.
> >        */
> > -     if (chan_rank_empty == GENMASK(chan_rank_max - 1, 0)) {
> > +     if (bitmap_full(chan_rank_empty, chan_rank_max)) {
> >               if (priv->no_dimm_retry_count < NO_DIMM_RETRY_COUNT_MAX) {
> >                       priv->no_dimm_retry_count++;
> >
> > @@ -274,14 +276,16 @@ static int check_populated_dimms(struct peci_dimmtemp *priv)
> >        * It's possible that memory training is not done yet. In this case we
> >        * defer the detection to be performed at a later point in time.
> >        */
> > -     if (!dimm_mask) {
> > +     if (bitmap_empty(dimm_mask, DIMM_NUMS_MAX)) {
> >               priv->no_dimm_retry_count = 0;
> >               return -EAGAIN;
> >       }
> >
> > -     dev_dbg(priv->dev, "Scanned populated DIMMs: %#x\n", dimm_mask);
> > +     for_each_set_bit(i, dimm_mask, DIMM_NUMS_MAX) {
> > +             dev_dbg(priv->dev, "Found DIMM%#x\n", i);
> > +     }
> >
> > -     bitmap_from_arr32(priv->dimm_mask, &dimm_mask, DIMM_NUMS_MAX);
> > +     bitmap_copy(priv->dimm_mask, dimm_mask, DIMM_NUMS_MAX);
> >
> >       return 0;
> >  }