linux-kernel - Re: [PATCH v2] soc: qcom: rpmh-rsc: Enhance check for VREG in-flight request

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Message-ID: <82e4796a-8983-4045-8ca2-71aa9af7a120@linaro.org>
Date: Fri, 19 Jan 2024 10:34:09 +0000
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: Maulik Shah <quic_mkshah@...cinc.com>,
 Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konrad.dybcio@...aro.org>
Cc: linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
 quic_eberman@...cinc.com, quic_collinsd@...cinc.com, quic_lsrao@...cinc.com
Subject: Re: [PATCH v2] soc: qcom: rpmh-rsc: Enhance check for VREG in-flight
 request

On 19/01/2024 08:26, Maulik Shah wrote:
> Each RPMh VREG accelerator resource has 3 or 4 contiguous 4-byte aligned
> addresses associated with it. These control voltage, enable state, mode,
> and in legacy targets, voltage headroom. The current in-flight request
> checking logic looks for exact address matches. Requests for different
> addresses of the same RPMh resource as thus not detected as in-flight.

This commit log implies you are fixing a bug.

Can you do some inspection of the git commit log and figure out where to 
backport this change to ?

Your change would apply to 40482e4f73640d but a quick pass on the logic 
in check_for_req_inflight() shows its probably _applicable_ to 
658628e7ef78e8

>   /*
>    * Here's a high level overview of how all the registers in RPMH work
>    * together:
> @@ -557,7 +568,15 @@ static int check_for_req_inflight(struct rsc_drv *drv, struct tcs_group *tcs,
>   		for_each_set_bit(j, &curr_enabled, MAX_CMDS_PER_TCS) {
>   			addr = read_tcs_cmd(drv, drv->regs[RSC_DRV_CMD_ADDR], i, j);
>   			for (k = 0; k < msg->num_cmds; k++) {
> -				if (addr == msg->cmds[k].addr)
> +				/*
> +				 * Each RPMh VREG accelerator resource has 3 or 4 contiguous 4-byte
> +				 * aligned addresses associated with it. Ignore the offset to check
> +				 * for in-flight VREG requests.
> +				 */
> +				if (ACCL_TYPE(msg->cmds[k].addr) == HW_ACCL_VREG &&
> +				    VREG_ADDR(msg->cmds[k].addr) == VREG_ADDR(addr))
> +					return -EBUSY;
> +				else if (addr == msg->cmds[k].addr)

Consider removing the /* comment */ if it helps to apply the change 
earlier than 658628e7ef78e8.

---
bod