Hi Tomi,
On Thu, Apr 29, 2021 at 02:57:23AM +0300, Laurent Pinchart wrote:
> On Mon, Apr 19, 2021 at 02:29:20PM +0300, Tomi Valkeinen wrote:
> > On 18/04/2021 15:46, Laurent Pinchart wrote:
> > > On Mon, Apr 12, 2021 at 02:34:44PM +0300, Tomi Valkeinen wrote:
> > >> Asserting ComplexIO reset seems to affect the HW (ie. asserting reset
> > >> will break an active capture), but the RESET_DONE bit never changes to
> > >> "reset is ongoing" state. Thus we always get a timeout.
> > >>
> > >> Drop the wait, as it seems to achieve nothing.
> > >>
> > >> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
> > >> ---
> > >> drivers/media/platform/ti-vpe/cal-camerarx.c | 15 ++-------------
> > >> 1 file changed, 2 insertions(+), 13 deletions(-)
> > >>
> > >> diff --git a/drivers/media/platform/ti-vpe/cal-camerarx.c b/drivers/media/platform/ti-vpe/cal-camerarx.c
> > >> index 0354f311c5d2..245c601b992c 100644
> > >> --- a/drivers/media/platform/ti-vpe/cal-camerarx.c
> > >> +++ b/drivers/media/platform/ti-vpe/cal-camerarx.c
> > >> @@ -405,7 +405,6 @@ static int cal_camerarx_start(struct cal_camerarx *phy)
> > >>
> > >> static void cal_camerarx_stop(struct cal_camerarx *phy)
> > >> {
> > >> - unsigned int i;
> > >> int ret;
> > >>
> > >> cal_camerarx_ppi_disable(phy);
> > >> @@ -419,19 +418,9 @@ static void cal_camerarx_stop(struct cal_camerarx *phy)
> > >> CAL_CSI2_COMPLEXIO_CFG_RESET_CTRL,
> > >> CAL_CSI2_COMPLEXIO_CFG_RESET_CTRL_MASK);
> > >>
> > >> - /* Wait for power down completion */
> > >> - for (i = 0; i < 10; i++) {
> > >> - if (cal_read_field(phy->cal,
> > >> - CAL_CSI2_COMPLEXIO_CFG(phy->instance),
> > >> - CAL_CSI2_COMPLEXIO_CFG_RESET_DONE_MASK) ==
> > >> - CAL_CSI2_COMPLEXIO_CFG_RESET_DONE_RESETONGOING)
> > >
> > > Isn't this the wrong condition ? I would have expected
> > > CAL_CSI2_COMPLEXIO_CFG_RESET_DONE_RESETCOMPLETED, not
> > > CAL_CSI2_COMPLEXIO_CFG_RESET_DONE_RESETONGOING. That could explain why
> > > you always get a timeout.
> >
> > No, I don't think so. The complexio reset is set active just before the
> > wait. So the reset status should show reset ongoing, until at some point
> > we release the reset (we do that when starting the PHY again).
> >
> > The TRM doesn't talk about this, though. So, I guess the status might go
> > to RESETONGOING for a very short time and back to RESETCOMPLETED before
> > the code can see the RESETONGOING. But I suspect the status just stays
> > at RESETCOMPLETED.
>
> The TRM is indeed not very clear. My understanding was that asserting
> RESET_CTRL initiates the reset, and RESET_DONE switches to 1 once the
> reset completes. There's however a note in the initialization sequence
> that states
>
> a. Deassert the CAMERARX reset:
> i. Set CAL_CSI2_COMPLEXIO_CFG_j[30] RESET_CTRL to 0x1.
> CAUTION
> For the CAL_CSI2_COMPLEXIO_CFG_j[29] RESET_DONE bit to be set to 0x1
> (reset completed), the external sensor must to be active and sending the
> MIPI HS BYTECLK (that is, RXBYTECLKHS clock).
>
> The RESET_DONE bit may thus only toggle when de-asserting the reset
> signal (by setting RESET_CTRL to 1). It would be useful to test that
> hypothesis by reading RESET_DONE just before setting RESET_CTRL to 1,
> and right after. I'd expect the values to be 0 and 1 respectively. If
> that's the case, then this patch is likely correct, so
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>
>
> The register macros are quite confusing by the way. We have
>
> #define CAL_CSI2_COMPLEXIO_CFG_RESET_CTRL_MASK BIT(30)
> #define CAL_CSI2_COMPLEXIO_CFG_RESET_CTRL 0
> #define CAL_CSI2_COMPLEXIO_CFG_RESET_CTRL_OPERATIONAL 1
>
> When reading the code, I thought
>
> cal_write_field(phy->cal, CAL_CSI2_COMPLEXIO_CFG(phy->instance),
> CAL_CSI2_COMPLEXIO_CFG_RESET_CTRL,
> CAL_CSI2_COMPLEXIO_CFG_RESET_CTRL_MASK)
>
> meant that we were setting the reset bit to 1. I would personally get
> rid of the _MASK suffixes for single bits, and use 0 and 1 in the code
> instead of CAL_CSI2_COMPLEXIO_CFG_RESET_CTRL and
> CAL_CSI2_COMPLEXIO_CFG_RESET_CTRL_OPERATIONAL.
Do you think this would be a good idea ? It can be done in a follow-up
patch.
--
Regards,
Laurent Pinchart
