Re: [PATCH v4 3/8] drm/mediatek: add shadow register support

From: YT Shen
Date: Tue Jul 19 2016 - 07:12:47 EST

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In reply to: Philipp Zabel: "Re: [PATCH v4 3/8] drm/mediatek: add shadow register support"
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Hi Philipp, CK,

Thanks for the review.

On Mon, 2016-07-18 at 10:36 +0200, Philipp Zabel wrote:
> Hi CK, YT,
>
> Am Montag, den 18.07.2016, 14:32 +0800 schrieb CK Hu:
> > Hi, YT:
> >
> > One comment inline.
> >
> >
> > On Fri, 2016-07-15 at 18:07 +0800, YT Shen wrote:
> > > We need to acquire mutex before using the resources,
> > > and need to release it after finished.
> > > So we don't need to write registers in the blanking period.
> > >
> > > Signed-off-by: YT Shen <yt.shen@xxxxxxxxxxxx>
> > > ---
> > > drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 75 +++++++++++++++++++------------
> > > drivers/gpu/drm/mediatek/mtk_drm_ddp.c | 22 +++++++++
> > > drivers/gpu/drm/mediatek/mtk_drm_ddp.h | 2 +
> > > drivers/gpu/drm/mediatek/mtk_drm_drv.h | 1 +
> > > 4 files changed, 71 insertions(+), 29 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > > index 24aa3ba..80d9641 100644
> > > --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > > +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > > @@ -315,6 +315,42 @@ static void mtk_crtc_ddp_hw_fini(struct mtk_drm_crtc *mtk_crtc)
> > > pm_runtime_put(drm->dev);
> > > }
> > >
> > > +static void mtk_crtc_ddp_config(struct drm_crtc *crtc)
> > > +{
> > > + struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
> > > + struct mtk_crtc_state *state = to_mtk_crtc_state(mtk_crtc->base.state);
> > > + struct mtk_ddp_comp *ovl = mtk_crtc->ddp_comp[0];
> > > + unsigned int i;
> > > +
> > > + /*
> > > + * TODO: instead of updating the registers here, we should prepare
> > > + * working registers in atomic_commit and let the hardware command
> > > + * queue update module registers on vblank.
> > > + */
> > > + if (state->pending_config) {
> > > + mtk_ddp_comp_config(ovl, state->pending_width,
> > > + state->pending_height,
> > > + state->pending_vrefresh);
> > > +
> > > + state->pending_config = false;
> > > + }
> > > +
> > > + if (mtk_crtc->pending_planes) {
> > > + for (i = 0; i < OVL_LAYER_NR; i++) {
> > > + struct drm_plane *plane = &mtk_crtc->planes[i].base;
> > > + struct mtk_plane_state *plane_state;
> > > +
> > > + plane_state = to_mtk_plane_state(plane->state);
> > > +
> > > + if (plane_state->pending.config) {
> > > + mtk_ddp_comp_layer_config(ovl, i, plane_state);
> > > + plane_state->pending.config = false;
> > > + }
> > > + }
> > > + mtk_crtc->pending_planes = false;
> > > + }
> > > +}
> > > +
> > > static void mtk_drm_crtc_enable(struct drm_crtc *crtc)
> > > {
> > > struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
> > > @@ -391,6 +427,7 @@ static void mtk_drm_crtc_atomic_flush(struct drm_crtc *crtc,
> > > struct drm_crtc_state *old_crtc_state)
> > > {
> > > struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
> > > + struct mtk_drm_private *priv = crtc->dev->dev_private;
> > > unsigned int pending_planes = 0;
> > > int i;
> > >
> > > @@ -409,6 +446,12 @@ static void mtk_drm_crtc_atomic_flush(struct drm_crtc *crtc,
> > > }
> > > if (pending_planes)
> > > mtk_crtc->pending_planes = true;
> > > +
> > > + if (priv->data->shadow_register) {
> > > + mtk_disp_mutex_acquire(mtk_crtc->mutex);
> > > + mtk_crtc_ddp_config(crtc);
> > > + mtk_disp_mutex_release(mtk_crtc->mutex);
> > > + }
> > > }
> > >
> > > static const struct drm_crtc_funcs mtk_crtc_funcs = {
> > > @@ -453,36 +496,10 @@ err_cleanup_crtc:
> > > void mtk_crtc_ddp_irq(struct drm_crtc *crtc, struct mtk_ddp_comp *ovl)
> > > {
> > > struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
> > > - struct mtk_crtc_state *state = to_mtk_crtc_state(mtk_crtc->base.state);
> > > - unsigned int i;
> > > + struct mtk_drm_private *priv = crtc->dev->dev_private;
> > >
> > > - /*
> > > - * TODO: instead of updating the registers here, we should prepare
> > > - * working registers in atomic_commit and let the hardware command
> > > - * queue update module registers on vblank.
> > > - */
> > > - if (state->pending_config) {
> > > - mtk_ddp_comp_config(ovl, state->pending_width,
> > > - state->pending_height,
> > > - state->pending_vrefresh);
> > > -
> > > - state->pending_config = false;
> > > - }
> > > -
> > > - if (mtk_crtc->pending_planes) {
> > > - for (i = 0; i < OVL_LAYER_NR; i++) {
> > > - struct drm_plane *plane = &mtk_crtc->planes[i].base;
> > > - struct mtk_plane_state *plane_state;
> > > -
> > > - plane_state = to_mtk_plane_state(plane->state);
> > > -
> > > - if (plane_state->pending.config) {
> > > - mtk_ddp_comp_layer_config(ovl, i, plane_state);
> > > - plane_state->pending.config = false;
> > > - }
> > > - }
> > > - mtk_crtc->pending_planes = false;
> > > - }
> > > + if (!priv->data->shadow_register)
> > > + mtk_crtc_ddp_config(crtc);
> > >
> > > mtk_drm_finish_page_flip(mtk_crtc);
> > > }
> > > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp.c b/drivers/gpu/drm/mediatek/mtk_drm_ddp.c
> > > index 8030769..fa53806 100644
> > > --- a/drivers/gpu/drm/mediatek/mtk_drm_ddp.c
> > > +++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp.c
> > > @@ -12,6 +12,7 @@
> > > */
> > >
> > > #include <linux/clk.h>
> > > +#include <linux/iopoll.h>
> > > #include <linux/module.h>
> > > #include <linux/of_device.h>
> > > #include <linux/platform_device.h>
> > > @@ -32,6 +33,7 @@
> > > #define DISP_REG_CONFIG_MMSYS_CG_CON0 0x100
> > >
> > > #define DISP_REG_MUTEX_EN(n) (0x20 + 0x20 * (n))
> > > +#define DISP_REG_MUTEX(n) (0x24 + 0x20 * (n))
> > > #define DISP_REG_MUTEX_RST(n) (0x28 + 0x20 * (n))
> > > #define DISP_REG_MUTEX_MOD(n) (0x2c + 0x20 * (n))
> > > #define DISP_REG_MUTEX_SOF(n) (0x30 + 0x20 * (n))
> > > @@ -300,6 +302,26 @@ void mtk_disp_mutex_disable(struct mtk_disp_mutex *mutex)
> > > writel(0, ddp->regs + DISP_REG_MUTEX_EN(mutex->id));
> > > }
> > >
> > > +void mtk_disp_mutex_acquire(struct mtk_disp_mutex *mutex)
> > > +{
> > > + struct mtk_ddp *ddp = container_of(mutex, struct mtk_ddp,
> > > + mutex[mutex->id]);
> > > + u32 tmp;
> > > +
> > > + writel(1, ddp->regs + DISP_REG_MUTEX_EN(mutex->id));
> > > + writel(1, ddp->regs + DISP_REG_MUTEX(mutex->id));
> > > + readl_poll_timeout_atomic(ddp->regs + DISP_REG_MUTEX(mutex->id), tmp,
> > > + tmp & 0x2, 1, 10000);
>
> Please add a descriptive #define for the 0x2 bit of the DISP_REG_MUTEX
> registers.
OK, will do.

>
> > Nothing to do with timeout? I think it should print error message here
> > or reset HW to recover it.
I will print error messages here for future debugging.

>
> I assume that if mtk_disp_mutex_acquire is called while the hardware has
> the mutex (during the shadow register update), this should wait until
> the update is complete, since it can't back out from trying to acquire
> the lock. Is that the case?
The acquire/release is handshake interface between software and hardware
to guarantee hardware receives a complete setting. If software wants to
modify registers, it needs set a request and wait acknowledge. And
after everything is done, software needs to notify hardware. As far as
I know, this timeout means hardware is wrong, eg: no output signals.

>
> regards
> Philipp
>

Next message: Songshan Gong: "[Question] for duplicate symbols, kallsyms and vmlinux may retain different symbol"
Previous message: YT Shen: "Re: [PATCH v4 4/8] drm/mediatek: add support for Mediatek SoC MT2701"
In reply to: Philipp Zabel: "Re: [PATCH v4 3/8] drm/mediatek: add shadow register support"
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