linux-kernel - RE: [PATCH v7][2/4] mmc: Add Synopsys DesignWare mmc cmdq host driver

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Message-ID: <49d0b19c5ec741638e41ee6f970d057b@realtek.com>
Date:   Mon, 11 Dec 2023 10:37:49 +0000
From:   Jyan Chou [周芷安] <jyanchou@...ltek.com>
To:     Adrian Hunter <adrian.hunter@...el.com>,
        "ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
        "jh80.chung@...sung.com" <jh80.chung@...sung.com>,
        "riteshh@...eaurora.org" <riteshh@...eaurora.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>
CC:     "conor+dt@...nel.org" <conor+dt@...nel.org>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "arnd@...db.de" <arnd@...db.de>,
        "briannorris@...omium.org" <briannorris@...omium.org>,
        "doug@...morgal.com" <doug@...morgal.com>,
        "tonyhuang.sunplus@...il.com" <tonyhuang.sunplus@...il.com>,
        "abel.vesa@...aro.org" <abel.vesa@...aro.org>,
        "william.qiu@...rfivetech.com" <william.qiu@...rfivetech.com>
Subject: RE: [PATCH v7][2/4] mmc: Add Synopsys DesignWare mmc cmdq host driver

Hi Adrian,

>>>> +
>>>> +static irqreturn_t dw_mci_cqe_interrupt(int irq, void *dev_id) {
>>>> +     struct dw_mci *host = dev_id;
>>>> +     struct mmc_host *mmc = host->slot->mmc;
>>>> +     struct cqhci_host *cq_host = NULL;
>>>> +     int cmd_error = 0, data_error = 0;
>>>> +
>>>> +     if (host->pdata && (host->pdata->caps2 & MMC_CAP2_CQE))
>>>> +             cq_host = mmc->cqe_private;
>>>> +
>>>> +     dw_mci_get_int(host);
>>>> +
>>>> +     if (host->pdata && (host->pdata->caps2 & MMC_CAP2_CQE)) {
>>>> +             if (!mmc->cqe_on && !cq_host->activated)
>>>
>>> Shouldn't really look at internals like mmc->cqe_on or cq_host->activated.
>>> There are the cqhci_host_ops ->enable() and ->disable() callbacks to
>>> keep track of whether cqhci is expecting interrupts.
>>
>> Does this means we need to use cqhci_host_ops ->enable() and
>> ->disable() callbacks instead of mmc->cqe_on && !cq_host->activated?
>Thanks.
>
>Yes.  ->enable() is always called before cqhci operation and ->disable() before
>non-cqhci operation, so they can be used to determine if an interrupt is for
>cqhci.

Thanks for your advice, and I got your point for calling cqhci_host_ops ->enable()

and ->disable() callbacks, but the reason we used " if (!mmc->cqe_on && !cq_host->activated) "

is that when sending command like cmd0, 1, 7, 8... in mmc_init_card before mmc_cmdq_enable,

we need to use interrupt in legacy mode, it is much better to write in this way?

+	events = mci_readw(host, NORMAL_INT_STAT_R);
- 	if (host->pdata && (host->pdata->caps2 & MMC_CAP2_CQE)) {
- 		if (!mmc->cqe_on && !cq_host->activated)
+	if (mmc->caps2 & MMC_CAP2_CQE) {
+		if (!(events & CQE_EVENT))
			dw_mci_clr_signal_int(host);

Using CQE_EVENT to determine whether Command Queue enable or not.

Many thanks.

Best Regards,
Jyan