linux-kernel - [PATCH v2] mtd: nand: raw: brcmnand: When oops in progress use pio and interrupt polling

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Message-Id: <1556809273-40009-1-git-send-email-kdasu.kdev@gmail.com>
Date:   Thu,  2 May 2019 11:01:01 -0400
From:   Kamal Dasu <kdasu.kdev@...il.com>
To:     linux-mtd@...ts.infradead.org
Cc:     bcm-kernel-feedback-list@...adcom.com,
        linux-kernel@...r.kernel.org, Kamal Dasu <kdasu.kdev@...il.com>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Marek Vasut <marek.vasut@...il.com>
Subject: [PATCH v2] mtd: nand: raw: brcmnand: When oops in progress use pio and interrupt polling

If mtd_oops is in progress, switch to polling during NAND command
completion instead of relying on DMA/interrupts so that the mtd_oops
buffer can be completely written in the assigned NAND partition.
This is needed in cases where and there is only one online CPU and
the panic is not on cpu0 as all IRQs are wired to cpu0.

Signed-off-by: Kamal Dasu <kdasu.kdev@...il.com>
---
 drivers/mtd/nand/raw/brcmnand/brcmnand.c | 55 ++++++++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
index 482c6f0..128a806 100644
--- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
@@ -823,6 +823,12 @@ static inline bool has_flash_dma(struct brcmnand_controller *ctrl)
 	return ctrl->flash_dma_base;
 }
 
+static inline void disable_flash_dma_xfer(struct brcmnand_controller *ctrl)
+{
+	if (has_flash_dma(ctrl))
+		ctrl->flash_dma_base = 0;
+}
+
 static inline bool flash_dma_buf_ok(const void *buf)
 {
 	return buf && !is_vmalloc_addr(buf) &&
@@ -1237,15 +1243,58 @@ static void brcmnand_cmd_ctrl(struct nand_chip *chip, int dat,
 	/* intentionally left blank */
 }
 
+static bool is_mtd_oops_in_progress(void)
+{
+	int i = 0;
+
+#ifdef CONFIG_MTD_OOPS
+	if (oops_in_progress && smp_processor_id()) {
+		int cpu = 0;
+
+		for_each_online_cpu(cpu)
+			++i;
+	}
+#endif
+	return (i == 1);
+}
+
+static bool brcmstb_nand_wait_for_completion(struct nand_chip *chip)
+{
+	struct brcmnand_host *host = nand_get_controller_data(chip);
+	struct brcmnand_controller *ctrl = host->ctrl;
+	bool err = false;
+	int sts;
+
+	if (is_mtd_oops_in_progress()) {
+		/* Switch to interrupt polling and PIO mode */
+		disable_flash_dma_xfer(ctrl);
+		sts = bcmnand_ctrl_poll_status(ctrl, NAND_CTRL_RDY |
+					       NAND_STATUS_READY,
+					       NAND_CTRL_RDY |
+					       NAND_STATUS_READY, 0);
+		err = (sts < 0) ? true : false;
+	} else {
+		unsigned long timeo = msecs_to_jiffies(
+						NAND_POLL_STATUS_TIMEOUT_MS);
+		/* wait for completion interrupt */
+		sts = wait_for_completion_timeout(&ctrl->done, timeo);
+		err = (sts <= 0) ? true : false;
+	}
+
+	return err;
+}
+
 static int brcmnand_waitfunc(struct nand_chip *chip)
 {
 	struct brcmnand_host *host = nand_get_controller_data(chip);
 	struct brcmnand_controller *ctrl = host->ctrl;
-	unsigned long timeo = msecs_to_jiffies(100);
+	bool err = false;
 
 	dev_dbg(ctrl->dev, "wait on native cmd %d\n", ctrl->cmd_pending);
-	if (ctrl->cmd_pending &&
-			wait_for_completion_timeout(&ctrl->done, timeo) <= 0) {
+	if (ctrl->cmd_pending)
+		err = brcmstb_nand_wait_for_completion(chip);
+
+	if (err) {
 		u32 cmd = brcmnand_read_reg(ctrl, BRCMNAND_CMD_START)
 					>> brcmnand_cmd_shift(ctrl);
 
-- 
1.9.0.138.g2de3478