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555701a45f
The rpmh-rsc code had both a driver-level lock (sometimes referred to in comments as drv->lock) and a lock per-TCS. The idea was supposed to be that there would be times where you could get by with just locking a TCS lock and therefor other RPMH users wouldn't be blocked. The above didn't work out so well. Looking at tcs_write() the bigger drv->lock was held for most of the function anyway. Only the __tcs_buffer_write() and __tcs_set_trigger() calls were called without holding the drv->lock. It actually turns out that in tcs_write() we don't need to hold the drv->lock for those function calls anyway even if the per-TCS lock isn't there anymore. From the newly added comments in the code, this is because: - We marked "tcs_in_use" under lock. - Once "tcs_in_use" has been marked nobody else could be writing to these registers until the interrupt goes off. - The interrupt can't go off until we trigger w/ the last line of __tcs_set_trigger(). Thus, from a tcs_write() point of view, the per-TCS lock was useless. Looking at rpmh_rsc_write_ctrl_data(), only the per-TCS lock was held. It turns out, though, that this function already needs to be called with the equivalent of the drv->lock held anyway (we either need to hold drv->lock as we will in a future patch or we need to know no other CPUs could be running as happens today). Specifically rpmh_rsc_write_ctrl_data() might be writing to a TCS that has been borrowed for writing an active transation but it never checks this. Let's eliminate this extra overhead and avoid possible AB BA locking headaches. Suggested-by: Maulik Shah <mkshah@codeaurora.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Link: https://lore.kernel.org/r/20200504104917.v6.4.Ib8dccfdb10bf6b1fb1d600ca1c21d9c0db1ef746@changeid Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
134 lines
4.5 KiB
C
134 lines
4.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (c) 2016-2018, The Linux Foundation. All rights reserved.
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*/
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#ifndef __RPM_INTERNAL_H__
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#define __RPM_INTERNAL_H__
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#include <linux/bitmap.h>
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#include <soc/qcom/tcs.h>
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#define TCS_TYPE_NR 4
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#define MAX_CMDS_PER_TCS 16
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#define MAX_TCS_PER_TYPE 3
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#define MAX_TCS_NR (MAX_TCS_PER_TYPE * TCS_TYPE_NR)
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#define MAX_TCS_SLOTS (MAX_CMDS_PER_TCS * MAX_TCS_PER_TYPE)
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struct rsc_drv;
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/**
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* struct tcs_group: group of Trigger Command Sets (TCS) to send state requests
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* to the controller
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*
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* @drv: The controller.
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* @type: Type of the TCS in this group - active, sleep, wake.
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* @mask: Mask of the TCSes relative to all the TCSes in the RSC.
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* @offset: Start of the TCS group relative to the TCSes in the RSC.
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* @num_tcs: Number of TCSes in this type.
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* @ncpt: Number of commands in each TCS.
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* @req: Requests that are sent from the TCS; only used for ACTIVE_ONLY
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* transfers (could be on a wake/sleep TCS if we are borrowing for
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* an ACTIVE_ONLY transfer).
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* Start: grab drv->lock, set req, set tcs_in_use, drop drv->lock,
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* trigger
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* End: get irq, access req,
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* grab drv->lock, clear tcs_in_use, drop drv->lock
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* @slots: Indicates which of @cmd_addr are occupied; only used for
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* SLEEP / WAKE TCSs. Things are tightly packed in the
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* case that (ncpt < MAX_CMDS_PER_TCS). That is if ncpt = 2 and
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* MAX_CMDS_PER_TCS = 16 then bit[2] = the first bit in 2nd TCS.
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*/
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struct tcs_group {
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struct rsc_drv *drv;
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int type;
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u32 mask;
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u32 offset;
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int num_tcs;
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int ncpt;
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const struct tcs_request *req[MAX_TCS_PER_TYPE];
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DECLARE_BITMAP(slots, MAX_TCS_SLOTS);
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};
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/**
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* struct rpmh_request: the message to be sent to rpmh-rsc
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*
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* @msg: the request
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* @cmd: the payload that will be part of the @msg
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* @completion: triggered when request is done
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* @dev: the device making the request
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* @err: err return from the controller
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* @needs_free: check to free dynamically allocated request object
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*/
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struct rpmh_request {
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struct tcs_request msg;
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struct tcs_cmd cmd[MAX_RPMH_PAYLOAD];
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struct completion *completion;
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const struct device *dev;
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int err;
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bool needs_free;
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};
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/**
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* struct rpmh_ctrlr: our representation of the controller
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*
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* @cache: the list of cached requests
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* @cache_lock: synchronize access to the cache data
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* @dirty: was the cache updated since flush
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* @batch_cache: Cache sleep and wake requests sent as batch
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*/
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struct rpmh_ctrlr {
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struct list_head cache;
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spinlock_t cache_lock;
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bool dirty;
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struct list_head batch_cache;
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};
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/**
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* struct rsc_drv: the Direct Resource Voter (DRV) of the
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* Resource State Coordinator controller (RSC)
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*
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* @name: Controller identifier.
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* @tcs_base: Start address of the TCS registers in this controller.
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* @id: Instance id in the controller (Direct Resource Voter).
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* @num_tcs: Number of TCSes in this DRV.
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* @rsc_pm: CPU PM notifier for controller.
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* Used when solver mode is not present.
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* @cpus_entered_pm: CPU mask for cpus in idle power collapse.
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* Used when solver mode is not present.
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* @tcs: TCS groups.
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* @tcs_in_use: S/W state of the TCS; only set for ACTIVE_ONLY
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* transfers, but might show a sleep/wake TCS in use if
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* it was borrowed for an active_only transfer. You
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* must hold the lock in this struct (AKA drv->lock) in
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* order to update this.
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* @lock: Synchronize state of the controller.
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* @pm_lock: Synchronize during PM notifications.
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* Used when solver mode is not present.
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* @client: Handle to the DRV's client.
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*/
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struct rsc_drv {
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const char *name;
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void __iomem *tcs_base;
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int id;
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int num_tcs;
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struct notifier_block rsc_pm;
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struct cpumask cpus_entered_pm;
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struct tcs_group tcs[TCS_TYPE_NR];
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DECLARE_BITMAP(tcs_in_use, MAX_TCS_NR);
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spinlock_t lock;
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spinlock_t pm_lock;
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struct rpmh_ctrlr client;
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};
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int rpmh_rsc_send_data(struct rsc_drv *drv, const struct tcs_request *msg);
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int rpmh_rsc_write_ctrl_data(struct rsc_drv *drv,
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const struct tcs_request *msg);
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void rpmh_rsc_invalidate(struct rsc_drv *drv);
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void rpmh_tx_done(const struct tcs_request *msg, int r);
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int rpmh_flush(struct rpmh_ctrlr *ctrlr);
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#endif /* __RPM_INTERNAL_H__ */
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