[PATCH 0/3] mmc: mmci: Restore irq handling behavior for arm_variant

[PATCH 0/3] mmc: mmci: Restore irq handling behavior for arm_variant

[Ulf Hansson]

Commit "mmc: mmci: Handle CMD irq before DATA irq" introduced a bug, reported
by John Stultz while using the arm_variant in QEMU envrionment.

More information can be found here:
https://lkml.org/lkml/2014/6/12/19

In this patchset we restores the old behavior for handling irqs, but only for
the arm_variant.

Ulf Hansson (3):
  mmc: mmci: Remove redundant check of status for DATA irq
  mmc: mmci: Move all CMD irq handling to mmci_cmd_irq()
  mmc: mmci: Reverse IRQ handling for the arm_variant

 drivers/mmc/host/mmci.c |   40 ++++++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 16 deletions(-)

-- 
1.7.9.5

[PATCH 1/3] mmc: mmci: Remove redundant check of status for DATA irq

[Ulf Hansson]

We don't need to verify the content of the status register twice, while
we are about to handle a DATA irq. Instead let's leave all verification
to be handled by mmci_data_irq().

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/mmc/host/mmci.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index 6483c5c..a723ed2 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -888,6 +888,10 @@ static void
 mmci_data_irq(struct mmci_host *host, struct mmc_data *data,
 	      unsigned int status)
 {
+	/* Make sure we have data to handle */
+	if (!data)
+		return;
+
 	/* First check for errors */
 	if (status & (MCI_DATACRCFAIL|MCI_DATATIMEOUT|MCI_STARTBITERR|
 		      MCI_TXUNDERRUN|MCI_RXOVERRUN)) {
@@ -1206,7 +1210,6 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
 
 	do {
 		struct mmc_command *cmd;
-		struct mmc_data *data;
 
 		status = readl(host->base + MMCISTATUS);
 
@@ -1232,11 +1235,7 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
 			MCI_CMDSENT|MCI_CMDRESPEND) && cmd)
 			mmci_cmd_irq(host, cmd, status);
 
-		data = host->data;
-		if (status & (MCI_DATACRCFAIL|MCI_DATATIMEOUT|MCI_STARTBITERR|
-			      MCI_TXUNDERRUN|MCI_RXOVERRUN|MCI_DATAEND|
-			      MCI_DATABLOCKEND) && data)
-			mmci_data_irq(host, data, status);
+		mmci_data_irq(host, host->data, status);
 
 		/* Don't poll for busy completion in irq context. */
 		if (host->busy_status)
-- 
1.7.9.5

[PATCH 2/3] mmc: mmci: Move all CMD irq handling to mmci_cmd_irq()

[Ulf Hansson]

This patch won't change the behavior of how mmci deals with CMD irqs.
By moving code from mmci_irq() to mmci_cmd_irq(), we getter a better
overview of what going on.

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/mmc/host/mmci.c |   22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index a723ed2..5d20bfba 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -960,9 +960,17 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd,
 	     unsigned int status)
 {
 	void __iomem *base = host->base;
-	bool sbc = (cmd == host->mrq->sbc);
-	bool busy_resp = host->variant->busy_detect &&
-			(cmd->flags & MMC_RSP_BUSY);
+	bool sbc, busy_resp;
+
+	if (!cmd)
+		return;
+
+	sbc = (cmd == host->mrq->sbc);
+	busy_resp = host->variant->busy_detect && (cmd->flags & MMC_RSP_BUSY);
+
+	if (!((status|host->busy_status) & (MCI_CMDCRCFAIL|MCI_CMDTIMEOUT|
+		MCI_CMDSENT|MCI_CMDRESPEND)))
+		return;
 
 	/* Check if we need to wait for busy completion. */
 	if (host->busy_status && (status & MCI_ST_CARDBUSY))
@@ -1209,8 +1217,6 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
 	spin_lock(&host->lock);
 
 	do {
-		struct mmc_command *cmd;
-
 		status = readl(host->base + MMCISTATUS);
 
 		if (host->singleirq) {
@@ -1230,11 +1236,7 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
 
 		dev_dbg(mmc_dev(host->mmc), "irq0 (data+cmd) %08x\n", status);
 
-		cmd = host->cmd;
-		if ((status|host->busy_status) & (MCI_CMDCRCFAIL|MCI_CMDTIMEOUT|
-			MCI_CMDSENT|MCI_CMDRESPEND) && cmd)
-			mmci_cmd_irq(host, cmd, status);
-
+		mmci_cmd_irq(host, host->cmd, status);
 		mmci_data_irq(host, host->data, status);
 
 		/* Don't poll for busy completion in irq context. */
-- 
1.7.9.5

[PATCH 3/3] mmc: mmci: Reverse IRQ handling for the arm_variant

[Ulf Hansson]

Commit "mmc: mmci: Handle CMD irq before DATA irq", caused an issue
when using the ARM model of the PL181 and running QEMU.

The bug was reported for the following QEMU version:
$ qemu-system-arm -version
QEMU emulator version 2.0.0 (Debian 2.0.0+dfsg-2ubuntu1.1), Copyright
(c) 2003-2008 Fabrice Bellard

To resolve the problem, let's restore the old behavior were the DATA
irq is handled prior the CMD irq, but only for the arm_variant, which
the problem was reported for.

Reported-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/mmc/host/mmci.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index 5d20bfba..c7e1d42 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -74,6 +74,7 @@ static unsigned int fmax = 515633;
  * @pwrreg_nopower: bits in MMCIPOWER don't controls ext. power supply
  * @explicit_mclk_control: enable explicit mclk control in driver.
  * @qcom_fifo: enables qcom specific fifo pio read logic.
+ * @reversed_irq_handling: handle data irq before cmd irq.
  */
 struct variant_data {
 	unsigned int		clkreg;
@@ -97,6 +98,7 @@ struct variant_data {
 	bool			pwrreg_nopower;
 	bool			explicit_mclk_control;
 	bool			qcom_fifo;
+	bool			reversed_irq_handling;
 };
 
 static struct variant_data variant_arm = {
@@ -1236,8 +1238,13 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
 
 		dev_dbg(mmc_dev(host->mmc), "irq0 (data+cmd) %08x\n", status);
 
-		mmci_cmd_irq(host, host->cmd, status);
-		mmci_data_irq(host, host->data, status);
+		if (host->variant->reversed_irq_handling) {
+			mmci_data_irq(host, host->data, status);
+			mmci_cmd_irq(host, host->cmd, status);
+		} else {
+			mmci_cmd_irq(host, host->cmd, status);
+			mmci_data_irq(host, host->data, status);
+		}
 
 		/* Don't poll for busy completion in irq context. */
 		if (host->busy_status)
-- 
1.7.9.5

[PATCH 3/3] mmc: mmci: Reverse IRQ handling for the arm_variant

[Ulf Hansson]

On 16 June 2014 09:58, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> Commit "mmc: mmci: Handle CMD irq before DATA irq", caused an issue
> when using the ARM model of the PL181 and running QEMU.
>
> The bug was reported for the following QEMU version:
> $ qemu-system-arm -version
> QEMU emulator version 2.0.0 (Debian 2.0.0+dfsg-2ubuntu1.1), Copyright
> (c) 2003-2008 Fabrice Bellard
>
> To resolve the problem, let's restore the old behavior were the DATA
> irq is handled prior the CMD irq, but only for the arm_variant, which
> the problem was reported for.
>
> Reported-by: John Stultz <john.stultz@linaro.org>
> Cc: Peter Maydell <peter.maydell@linaro.org>
> Cc: Russell King <linux@arm.linux.org.uk>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>  drivers/mmc/host/mmci.c |   11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> index 5d20bfba..c7e1d42 100644
> --- a/drivers/mmc/host/mmci.c
> +++ b/drivers/mmc/host/mmci.c
> @@ -74,6 +74,7 @@ static unsigned int fmax = 515633;
>   * @pwrreg_nopower: bits in MMCIPOWER don't controls ext. power supply
>   * @explicit_mclk_control: enable explicit mclk control in driver.
>   * @qcom_fifo: enables qcom specific fifo pio read logic.
> + * @reversed_irq_handling: handle data irq before cmd irq.
>   */
>  struct variant_data {
>         unsigned int            clkreg;
> @@ -97,6 +98,7 @@ struct variant_data {
>         bool                    pwrreg_nopower;
>         bool                    explicit_mclk_control;
>         bool                    qcom_fifo;
> +       bool                    reversed_irq_handling;
>  };

I noticed that I should enable reversed_irq_handling for the
arm_variant as well.

Will send a v2 in a moment.

Kind regards
Ulf Hansson

>
>  static struct variant_data variant_arm = {
> @@ -1236,8 +1238,13 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
>
>                 dev_dbg(mmc_dev(host->mmc), "irq0 (data+cmd) %08x\n", status);
>
> -               mmci_cmd_irq(host, host->cmd, status);
> -               mmci_data_irq(host, host->data, status);
> +               if (host->variant->reversed_irq_handling) {
> +                       mmci_data_irq(host, host->data, status);
> +                       mmci_cmd_irq(host, host->cmd, status);
> +               } else {
> +                       mmci_cmd_irq(host, host->cmd, status);
> +                       mmci_data_irq(host, host->data, status);
> +               }
>
>                 /* Don't poll for busy completion in irq context. */
>                 if (host->busy_status)
> --
> 1.7.9.5
>