linux-kernel - Re: [PATCH v3 1/2] soc: qcom: smp2p: Add irqchip state support

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Message-ID: <65de918d-9608-43e6-890d-16672305a2b2@oss.qualcomm.com>
Date: Fri, 30 Jan 2026 11:13:56 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Chris Lew <christopher.lew@....qualcomm.com>,
        Deepak Kumar Singh <deepak.singh@....qualcomm.com>
Cc: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        Chris Lew <chris.lew@....qualcomm.com>
Subject: Re: [PATCH v3 1/2] soc: qcom: smp2p: Add irqchip state support

On 1/30/26 1:46 AM, Chris Lew wrote:
> On Thu, Jan 29, 2026 at 04:26:38PM +0530, Deepak Kumar Singh wrote:
>>
>> On 1/27/2026 6:25 PM, Konrad Dybcio wrote:
>>> On 1/27/26 11:38 AM, Deepak Kumar Singh wrote:
>>>> From: Chris Lew <chris.lew@....qualcomm.com>
>>>>
>>>> A remoteproc booted during earlier boot stages such as UEFI or the
>>>> bootloader, may need to be attached to without restarting the remoteproc
>>>> hardware. To do this the remoteproc will need to check the ready and
>>>> handover states in smp2p without an interrupt notification. Create
>>>> qcom_smp2p_start_in() to initialize the shadow state without notifying
>>>> clients because these early events happened in the past.
>>>>
>>>> Add support for the .irq_get_irqchip_state callback so remoteproc can
>>>> read the current state of the fatal, ready and handover bits.
>>>>
>>>> Signed-off-by: Chris Lew <chris.lew@....qualcomm.com>
>>>> Signed-off-by: Deepak Kumar Singh <deepak.singh@....qualcomm.com>
>>>> ---
>>>>   drivers/soc/qcom/smp2p.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++
>>>>   1 file changed, 55 insertions(+)
>>>>
>>>> diff --git a/drivers/soc/qcom/smp2p.c b/drivers/soc/qcom/smp2p.c
>>>> index cb515c2340c1..c27ffb44b825 100644
>>>> --- a/drivers/soc/qcom/smp2p.c
>>>> +++ b/drivers/soc/qcom/smp2p.c
>>>> @@ -222,6 +222,39 @@ static void qcom_smp2p_negotiate(struct qcom_smp2p *smp2p)
>>>>   	}
>>>>   }
>>>> +static void qcom_smp2p_start_in(struct qcom_smp2p *smp2p)
>>>> +{
>>>> +	unsigned int smem_id = smp2p->smem_items[SMP2P_INBOUND];
>>>> +	unsigned int pid = smp2p->remote_pid;
>>>> +	char buf[SMP2P_MAX_ENTRY_NAME];
>>>> +	struct smp2p_smem_item *in;
>>>> +	struct smp2p_entry *entry;
>>>> +	size_t size;
>>>> +	int i;
>>>> +
>>>> +	in = qcom_smem_get(pid, smem_id, &size);
>>>> +	if (IS_ERR(in))
>>>> +		return;
>>>> +
>>>> +	smp2p->in = in;
>>>> +
>>>> +	/* Check if version is initialized by the remote. */
>>>> +	if (in->version == 0)
>>>> +		return;
>>>> +
>>>> +	for (i = smp2p->valid_entries; i < in->valid_entries; i++) {
>>>> +		list_for_each_entry(entry, &smp2p->inbound, node) {
>>>> +			memcpy(buf, in->entries[i].name, sizeof(buf));
>>> Is there a reason for this copy at all?
>> I don't see a compelling reason. This code snippet is same as present in
>> qcom_smp2p_notify_in().
> 
> My understanding was that we do this copy because we don't want to do a
> strcmp on memory that the remote could change at any time. Maybe it's
> overkill but I thought it was considered good practice and as Deepak
> mentioned, it is similarly present in qcom_smp2p_notify_in().

Ok, right, I didn't take that into account

Konrad