mfd: rtsx: Optimize card detect flow

1. Schedule card detect work at the end of the ISR
2. Callback function ops->cd_deglitch may delay for a period of time.
It is not proper to call this callback when local irq disabled.
3. Card detect flow can't be executed in parallel with other card reader
operations, so it's better to be protected by mutex.
Signed-off-by: Wei WANG <wei_wang@realsil.com.cn>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/rtsx_pcr.c

@@ -752,7 +752,7 @@ static void rtsx_pci_card_detect(struct work_struct *work)
 	struct delayed_work *dwork;
 	struct rtsx_pcr *pcr;
 	unsigned long flags;
-	unsigned int card_detect = 0;
+	unsigned int card_detect = 0, card_inserted, card_removed;
 	u32 irq_status;
 
 	dwork = to_delayed_work(work);
@@ -760,25 +760,32 @@ static void rtsx_pci_card_detect(struct work_struct *work)
 
 	dev_dbg(&(pcr->pci->dev), "--> %s\n", __func__);
 
+	mutex_lock(&pcr->pcr_mutex);
 	spin_lock_irqsave(&pcr->lock, flags);
 
 	irq_status = rtsx_pci_readl(pcr, RTSX_BIPR);
 	dev_dbg(&(pcr->pci->dev), "irq_status: 0x%08x\n", irq_status);
 
-	if (pcr->card_inserted || pcr->card_removed) {
+	irq_status &= CARD_EXIST;
+	card_inserted = pcr->card_inserted & irq_status;
+	card_removed = pcr->card_removed;
+	pcr->card_inserted = 0;
+	pcr->card_removed = 0;
+
+	spin_unlock_irqrestore(&pcr->lock, flags);
+
+	if (card_inserted || card_removed) {
 		dev_dbg(&(pcr->pci->dev),
 				"card_inserted: 0x%x, card_removed: 0x%x\n",
-				pcr->card_inserted, pcr->card_removed);
+				card_inserted, card_removed);
 
 		if (pcr->ops->cd_deglitch)
-			pcr->card_inserted = pcr->ops->cd_deglitch(pcr);
+			card_inserted = pcr->ops->cd_deglitch(pcr);
 
-		card_detect = pcr->card_inserted | pcr->card_removed;
-		pcr->card_inserted = 0;
-		pcr->card_removed = 0;
+		card_detect = card_inserted | card_removed;
 	}
 
-	spin_unlock_irqrestore(&pcr->lock, flags);
+	mutex_unlock(&pcr->pcr_mutex);
 
 	if ((card_detect & SD_EXIST) && pcr->slots[RTSX_SD_CARD].card_event)
 		pcr->slots[RTSX_SD_CARD].card_event(
@@ -830,10 +837,6 @@ static irqreturn_t rtsx_pci_isr(int irq, void *dev_id)
 		}
 	}
 
-	if (pcr->card_inserted || pcr->card_removed)
-		schedule_delayed_work(&pcr->carddet_work,
-				msecs_to_jiffies(200));
-
 	if (int_reg & (NEED_COMPLETE_INT | DELINK_INT)) {
 		if (int_reg & (TRANS_FAIL_INT | DELINK_INT)) {
 			pcr->trans_result = TRANS_RESULT_FAIL;
@@ -846,6 +849,10 @@ static irqreturn_t rtsx_pci_isr(int irq, void *dev_id)
 		}
 	}
 
+	if (pcr->card_inserted || pcr->card_removed)
+		schedule_delayed_work(&pcr->carddet_work,
+				msecs_to_jiffies(200));
+
 	spin_unlock(&pcr->lock);
 	return IRQ_HANDLED;
 }