Re: [PATCH V2 3/5] mmc: mmci: fix clear of busy detect status
From: Ulf Hansson
Date: Wed May 29 2019 - 06:40:56 EST
On Wed, 29 May 2019 at 11:20, Ludovic BARRE <ludovic.barre@xxxxxx> wrote:
> 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
> 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
> 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 ?
Right, I see your point.
On the other hand, that re-read of the status registers should really
not be needed. Maybe it's a leftover from my initial version of the
code, but in any case we should remove that.
> > 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