From: Michael Ellerman <mpe@ellerman•id.au>
To: Pratik Rajesh Sampat <psampat@linux•ibm.com>,
linux-kernel@vger•kernel.org, linuxppc-dev@ozlabs•org,
svaidy@linux•ibm.com, ego@linux•vnet.ibm.com,
linuxram@us•ibm.com, pratik.sampat@in•ibm.com,
psampat@linux•ibm.com, pratik.r.sampat@gmail•com
Subject: Re: [PATCH v4 3/3] powerpc/powernv: Parse device tree, population of SPR support
Date: Tue, 17 Mar 2020 14:13:31 +1100 [thread overview]
Message-ID: <87tv2nptb8.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <1f5138b5080606804162b0a7cf20c134589b96b1.1581505210.git.psampat@linux.ibm.com>
Pratik Rajesh Sampat <psampat@linux•ibm.com> writes:
> Parse the device tree for nodes self-save, self-restore and populate
> support for the preferred SPRs based what was advertised by the device
> tree.
These should be documented in:
Documentation/devicetree/bindings/powerpc/opal/power-mgt.txt
> diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
> index 97aeb45e897b..27dfadf609e8 100644
> --- a/arch/powerpc/platforms/powernv/idle.c
> +++ b/arch/powerpc/platforms/powernv/idle.c
> @@ -1436,6 +1436,85 @@ static void __init pnv_probe_idle_states(void)
> supported_cpuidle_states |= pnv_idle_states[i].flags;
> }
>
> +/*
> + * Extracts and populates the self save or restore capabilities
> + * passed from the device tree node
> + */
> +static int extract_save_restore_state_dt(struct device_node *np, int type)
> +{
> + int nr_sprns = 0, i, bitmask_index;
> + int rc = 0;
> + u64 *temp_u64;
> + u64 bit_pos;
> +
> + nr_sprns = of_property_count_u64_elems(np, "sprn-bitmask");
> + if (nr_sprns <= 0)
> + return rc;
Using <= 0 means zero SPRs is treated by success as the caller, is that
intended? If so a comment would be appropriate.
> + temp_u64 = kcalloc(nr_sprns, sizeof(u64), GFP_KERNEL);
> + if (of_property_read_u64_array(np, "sprn-bitmask",
> + temp_u64, nr_sprns)) {
> + pr_warn("cpuidle-powernv: failed to find registers in DT\n");
> + kfree(temp_u64);
> + return -EINVAL;
> + }
> + /*
> + * Populate acknowledgment of support for the sprs in the global vector
> + * gotten by the registers supplied by the firmware.
> + * The registers are in a bitmask, bit index within
> + * that specifies the SPR
> + */
> + for (i = 0; i < nr_preferred_sprs; i++) {
> + bitmask_index = preferred_sprs[i].spr / 64;
> + bit_pos = preferred_sprs[i].spr % 64;
This is basically a hand coded bitmap, see eg. BIT_WORD(), BIT_MASK() etc.
I don't think there's an easy way to convert temp_u64 into a proper
bitmap, so it's probably not worth doing that. But at least use the macros.
> + if ((temp_u64[bitmask_index] & (1UL << bit_pos)) == 0) {
> + if (type == SELF_RESTORE_TYPE)
> + preferred_sprs[i].supported_mode &=
> + ~SELF_RESTORE_STRICT;
> + else
> + preferred_sprs[i].supported_mode &=
> + ~SELF_SAVE_STRICT;
> + continue;
> + }
> + if (type == SELF_RESTORE_TYPE) {
> + preferred_sprs[i].supported_mode |=
> + SELF_RESTORE_STRICT;
> + } else {
> + preferred_sprs[i].supported_mode |=
> + SELF_SAVE_STRICT;
> + }
> + }
> +
> + kfree(temp_u64);
> + return rc;
> +}
> +
> +static int pnv_parse_deepstate_dt(void)
> +{
> + struct device_node *sr_np, *ss_np;
You never use these concurrently AFAICS, so you could just have a single *np.
> + int rc = 0, i;
> +
> + /* Self restore register population */
> + sr_np = of_find_node_by_path("/ibm,opal/power-mgt/self-restore");
I know the existing idle code uses of_find_node_by_path(), but that's
because it's old and crufty. Please don't add new searches by path. You
should be searching by compatible.
> + if (!sr_np) {
> + pr_warn("opal: self restore Node not found");
This warning and the others below will fire on all existing firmware
versions, which is not OK.
> + } else {
> + rc = extract_save_restore_state_dt(sr_np, SELF_RESTORE_TYPE);
> + if (rc != 0)
> + return rc;
> + }
> + /* Self save register population */
> + ss_np = of_find_node_by_path("/ibm,opal/power-mgt/self-save");
> + if (!ss_np) {
> + pr_warn("opal: self save Node not found");
> + pr_warn("Legacy firmware. Assuming default self-restore support");
> + for (i = 0; i < nr_preferred_sprs; i++)
> + preferred_sprs[i].supported_mode &= ~SELF_SAVE_STRICT;
> + } else {
> + rc = extract_save_restore_state_dt(ss_np, SELF_SAVE_TYPE);
> + }
> + return rc;
You're leaking references on all the device_nodes in here, you need
of_node_put() before exiting.
> +}
cheers
next prev parent reply other threads:[~2020-03-17 3:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-12 11:20 [PATCH v4 0/3] Introduce Self-Save API for deep stop states Pratik Rajesh Sampat
2020-02-12 11:20 ` [PATCH v4 1/3] powerpc/powernv: Interface to define support and preference for a SPR Pratik Rajesh Sampat
2020-02-12 11:20 ` [PATCH v4 2/3] powerpc/powernv: Introduce Self save support Pratik Rajesh Sampat
2020-02-12 11:20 ` [PATCH v4 3/3] powerpc/powernv: Parse device tree, population of SPR support Pratik Rajesh Sampat
2020-03-17 3:13 ` Michael Ellerman [this message]
2020-03-17 14:08 ` Pratik Sampat
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87tv2nptb8.fsf@mpe.ellerman.id.au \
--to=mpe@ellerman$(echo .)id.au \
--cc=ego@linux$(echo .)vnet.ibm.com \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=linuxppc-dev@ozlabs$(echo .)org \
--cc=linuxram@us$(echo .)ibm.com \
--cc=pratik.r.sampat@gmail$(echo .)com \
--cc=pratik.sampat@in$(echo .)ibm.com \
--cc=psampat@linux$(echo .)ibm.com \
--cc=svaidy@linux$(echo .)ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox