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Date:   Thu, 30 Sep 2021 10:29:11 -0700
From:   Bjorn Andersson <bjorn.andersson@linaro.org>
To:     Deepak Kumar Singh <deesin@codeaurora.org>
Cc:     clew@codeaurora.org, linux-kernel@vger.kernel.org,
        linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org,
        Andy Gross <agross@kernel.org>
Subject: Re: [PATCH V1 1/1] soc: qcom: smp2p: add feature negotiation and ssr
 ack feature support
Message-ID: <YVXz54+pZfC+hGFI@ripper>
References: <1633019111-9318-1-git-send-email-deesin@codeaurora.org>
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In-Reply-To: <1633019111-9318-1-git-send-email-deesin@codeaurora.org>
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On Thu 30 Sep 09:25 PDT 2021, Deepak Kumar Singh wrote:

> This patch adds feature negotiation and ssr ack feature between
> local and remote host. Local host can negotiate on common features
> supported with remote host.
> 

This states that you're negotiating features, but doesn't capture the
actual ssr ack; why it's there and how it works.

> Signed-off-by: Chris Lew <clew@codeaurora.org>

Author of the patch should be Chris, please commit with --author
"Chris.."

> Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org>
> ---
>  drivers/soc/qcom/smp2p.c | 128 ++++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 103 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/soc/qcom/smp2p.c b/drivers/soc/qcom/smp2p.c
> index 38585a7..c1a60016 100644
> --- a/drivers/soc/qcom/smp2p.c
> +++ b/drivers/soc/qcom/smp2p.c
> @@ -41,8 +41,11 @@
>  #define SMP2P_MAX_ENTRY_NAME 16
>  
>  #define SMP2P_FEATURE_SSR_ACK 0x1
> +#define SMP2P_FLAGS_RESTART_DONE_BIT 0
> +#define SMP2P_FLAGS_RESTART_ACK_BIT 1
>  
>  #define SMP2P_MAGIC 0x504d5324
> +#define SMP2P_FEATURES	SMP2P_FEATURE_SSR_ACK

Rename this SMP2P_ALL_FEATURES?

>  
>  /**
>   * struct smp2p_smem_item - in memory communication structure
> @@ -136,6 +139,10 @@ struct qcom_smp2p {
>  
>  	unsigned valid_entries;
>  
> +	bool ssr_ack_enabled;
> +	bool ssr_ack;
> +	bool open;

How about renaming this "negotiation_done"?

> +
>  	unsigned local_pid;
>  	unsigned remote_pid;
>  
> @@ -163,22 +170,59 @@ static void qcom_smp2p_kick(struct qcom_smp2p *smp2p)
>  	}
>  }
>  
> -/**
> - * qcom_smp2p_intr() - interrupt handler for incoming notifications
> - * @irq:	unused
> - * @data:	smp2p driver context
> - *
> - * Handle notifications from the remote side to handle newly allocated entries
> - * or any changes to the state bits of existing entries.
> - */
> -static irqreturn_t qcom_smp2p_intr(int irq, void *data)
> +static bool qcom_smp2p_check_ssr(struct qcom_smp2p *smp2p)
> +{
> +	struct smp2p_smem_item *in = smp2p->in;
> +	bool restart;
> +
> +	if (!smp2p->ssr_ack_enabled)
> +		return false;
> +
> +	restart = in->flags & BIT(SMP2P_FLAGS_RESTART_DONE_BIT);

	return restart != smp2p->ssr_ack;

> +	if (restart == smp2p->ssr_ack)
> +		return false;
> +
> +	return true;
> +}
> +
> +static void qcom_smp2p_do_ssr_ack(struct qcom_smp2p *smp2p)
> +{
> +	struct smp2p_smem_item *out = smp2p->out;
> +	u32 ack;
> +	u32 val;
> +
> +	ack = !smp2p->ssr_ack;
> +	smp2p->ssr_ack = ack;
> +	ack = ack << SMP2P_FLAGS_RESTART_ACK_BIT;
> +
> +	val = out->flags & ~BIT(SMP2P_FLAGS_RESTART_ACK_BIT);
> +	val |= ack;
> +	out->flags = val;

I think this would be cleaner as:

	smp2p->ssr_ack = !smp2p->ssr_ack;

	val = out->flags & ~BIT(SMP2P_FLAGS_RESTART_ACK_BIT);
	if (smp2p->ssr_ack)
		val |= BIT(SMP2P_FLAGS_RESTART_ACK_BIT);
	out->flags = val;

> +
> +	qcom_smp2p_kick(smp2p);
> +}
> +
> +static void qcom_smp2p_negotiate(struct qcom_smp2p *smp2p)
> +{
> +	struct smp2p_smem_item *out = smp2p->out;
> +	struct smp2p_smem_item *in = smp2p->in;
> +	u32 features;
> +
> +	if (in->version == out->version) {
> +		features = in->features & out->features;
> +		out->features = features;

		out->features &= in->features;
> +
> +		if (features & SMP2P_FEATURE_SSR_ACK)

		if (out->features & SMP2P_FEATURE_SSR_ACK)

> +			smp2p->ssr_ack_enabled = true;
> +
> +		smp2p->open = true;
> +	}
> +}
> +
> +static void qcom_smp2p_notify_in(struct qcom_smp2p *smp2p)
>  {
>  	struct smp2p_smem_item *in;
>  	struct smp2p_entry *entry;
> -	struct qcom_smp2p *smp2p = data;
> -	unsigned smem_id = smp2p->smem_items[SMP2P_INBOUND];
> -	unsigned pid = smp2p->remote_pid;
> -	size_t size;
>  	int irq_pin;
>  	u32 status;
>  	char buf[SMP2P_MAX_ENTRY_NAME];
> @@ -187,18 +231,6 @@ static irqreturn_t qcom_smp2p_intr(int irq, void *data)
>  
>  	in = smp2p->in;
>  
> -	/* Acquire smem item, if not already found */
> -	if (!in) {
> -		in = qcom_smem_get(pid, smem_id, &size);
> -		if (IS_ERR(in)) {
> -			dev_err(smp2p->dev,
> -				"Unable to acquire remote smp2p item\n");
> -			return IRQ_HANDLED;
> -		}
> -
> -		smp2p->in = in;
> -	}
> -
>  	/* Match newly created entries */
>  	for (i = smp2p->valid_entries; i < in->valid_entries; i++) {
>  		list_for_each_entry(entry, &smp2p->inbound, node) {
> @@ -237,7 +269,52 @@ static irqreturn_t qcom_smp2p_intr(int irq, void *data)
>  			}
>  		}
>  	}
> +}
> +
> +/**
> + * qcom_smp2p_intr() - interrupt handler for incoming notifications
> + * @irq:	unused
> + * @data:	smp2p driver context
> + *
> + * Handle notifications from the remote side to handle newly allocated entries
> + * or any changes to the state bits of existing entries.
> + */
> +static irqreturn_t qcom_smp2p_intr(int irq, void *data)
> +{
> +	struct smp2p_smem_item *in;
> +	struct qcom_smp2p *smp2p = data;
> +	unsigned int smem_id = smp2p->smem_items[SMP2P_INBOUND];
> +	unsigned int pid = smp2p->remote_pid;
> +	size_t size;
> +
> +	in = smp2p->in;
> +
> +	/* Acquire smem item, if not already found */
> +	if (!in) {
> +		in = qcom_smem_get(pid, smem_id, &size);
> +		if (IS_ERR(in)) {
> +			dev_err(smp2p->dev,
> +				"Unable to acquire remote smp2p item\n");
> +			goto out;
> +		}
> +
> +		smp2p->in = in;
> +	}
> +
> +	if (!smp2p->open)
> +		qcom_smp2p_negotiate(smp2p);
> +
> +	if (smp2p->open) {
> +		bool do_restart;

How about "ack_restart" or "need_ack"?

While valid, can you please move the declaration to the top of the
function, to follow the style.

Regards,
Bjorn

> +
> +		do_restart = qcom_smp2p_check_ssr(smp2p);
> +		qcom_smp2p_notify_in(smp2p);
> +
> +		if (do_restart)
> +			qcom_smp2p_do_ssr_ack(smp2p);
> +	}
>  
> +out:
>  	return IRQ_HANDLED;
>  }
>  
> @@ -393,6 +470,7 @@ static int qcom_smp2p_alloc_outbound_item(struct qcom_smp2p *smp2p)
>  	out->remote_pid = smp2p->remote_pid;
>  	out->total_entries = SMP2P_MAX_ENTRY;
>  	out->valid_entries = 0;
> +	out->features = SMP2P_FEATURES;
>  
>  	/*
>  	 * Make sure the rest of the header is written before we validate the
> -- 
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> a Linux Foundation Collaborative Project
>