Re: [PATCH V2 3/5] mmc: mmci: fix clear of busy detect status

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hi Ulf

On 5/27/19 8:17 PM, Ulf Hansson wrote:
On Fri, 26 Apr 2019 at 09:46, Ludovic Barre <ludovic.Barre@xxxxxx> wrote:

From: Ludovic Barre <ludovic.barre@xxxxxx>

The "busy_detect_flag" is used to read/clear busy value of
mmci status. The "busy_detect_mask" is used to manage busy irq of
mmci mask.
For sdmmc variant, the 2 properties have not the same offset.
To clear the busyd0 status bit, we must add busy detect flag,
the mmci mask is not enough.

Signed-off-by: Ludovic Barre <ludovic.barre@xxxxxx>

Ludovic, again, apologies for the delay.

---
  drivers/mmc/host/mmci.c | 3 ++-
  1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index a040f54..3cd52e8 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -1517,7 +1517,8 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
                  * to make sure that both start and end interrupts are always
                  * cleared one after the other.
                  */
-               status &= readl(host->base + MMCIMASK0);
+               status &= readl(host->base + MMCIMASK0) |
+                       host->variant->busy_detect_flag;

I think this is not entirely correct, because it would mean we check
for busy even if we haven't unmasked the busy IRQ via the
variant->busy_detect_mask.

if the variant is busy_detect false:
 => no problem because the busy_detect_flag or busy_detect_mask is not
    defined.

if variant is busy_detect true:
the busy handle is split in 3 steps (see mmci_cmd_irq):
step 1: detection of busy line => unmasked the busy irq end
step 2: in busy wait => ignore cmd irq while current busy flag is
enabled.
step 3: end of busy => clear and mask busy irq

To detect the first step (see mmci_cmd_irq: which unmasks the busy irq)
we need to know the current busy state. Actually, the status register is
re-read in mmci_cmd_irq, why not used the status read in mmci_irq and in
parameter ?

Regards,
Ludo


I suggest to store a new bool in the host (call it
"busy_detect_unmasked" or whatever makes sense to you), to track
whether we have unmasked the busy IRQ or not. Then take this flag into
account, before ORing the value of host->variant->busy_detect_flag,
according to above.

                 if (host->variant->busy_detect)
                         writel(status & ~host->variant->busy_detect_mask,
                                host->base + MMCICLEAR);
--
2.7.4


Kind regards
Uffe




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