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SubjectRe: [PATCH v7 3/5] drm/mali-dp: Add writeback support for DP500.
On Fri, May 18, 2018 at 09:56:20AM +0100, Brian Starkey wrote:
> Hi Liviu,
>
> On Fri, May 18, 2018 at 09:24:21AM +0100, Liviu Dudau wrote:
> > Mali DP500 behaves differently from the rest of the Mali DP IP,
> > in that it does not have a one-shot mode and keeps writing the
> > content of the current frame to the provided memory area until
> > stopped. As a way of emulating the one-shot behaviour, we are
> > going to use the CVAL interrupt that is being raised at the
> > start of each frame, during prefetch phase, to act as End-of-Write
> > signal, but with a twist: we are going to disable the memory
> > write engine right after we're notified that it has been enabled,
> > using the knowledge that the bit controlling the enabling will
> > only be acted upon on the next vblank/prefetch.
> >
> > CVAL interrupt will fire durint the next prefetch phase every time
> > the global CVAL bit gets set, so we need a state byte to track
> > the memory write enabling.
> >
> > Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
> > ---
> > drivers/gpu/drm/arm/malidp_hw.c | 77 +++++++++++++++++++++++++++++--
> > drivers/gpu/drm/arm/malidp_hw.h | 5 +-
> > drivers/gpu/drm/arm/malidp_regs.h | 3 +-
> > 3 files changed, 80 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/arm/malidp_hw.c b/drivers/gpu/drm/arm/malidp_hw.c
> > index 455a83689d039..d9a7f19c9f219 100644
> > --- a/drivers/gpu/drm/arm/malidp_hw.c
> > +++ b/drivers/gpu/drm/arm/malidp_hw.c
> > @@ -22,6 +22,13 @@
> > #include "malidp_drv.h"
> > #include "malidp_hw.h"
> >
> > +enum {
> > + MW_NOT_ENABLED = 0, /* SE writeback not enabled */
> > + MW_ONESHOT, /* SE in one-shot mode for writeback */
> > + MW_START, /* SE started writeback */
> > + MW_STOP, /* SE finished writeback */
> > +};
> > +
> > static const struct malidp_format_id malidp500_de_formats[] = {
> > /* fourcc, layers supporting the format, internal id */
> > { DRM_FORMAT_ARGB2101010, DE_VIDEO1 | DE_GRAPHICS1 | DE_GRAPHICS2, 0 },
> > @@ -368,6 +375,50 @@ static long malidp500_se_calc_mclk(struct malidp_hw_device *hwdev,
> > return ret;
> > }
> >
> > +static int malidp500_enable_memwrite(struct malidp_hw_device *hwdev,
> > + dma_addr_t *addrs, s32 *pitches,
> > + int num_planes, u16 w, u16 h, u32 fmt_id)
> > +{
> > + u32 base = MALIDP500_SE_MEMWRITE_BASE;
> > + u32 de_base = malidp_get_block_base(hwdev, MALIDP_DE_BLOCK);
> > +
> > + /* enable the scaling engine block */
> > + malidp_hw_setbits(hwdev, MALIDP_SCALE_ENGINE_EN, de_base + MALIDP_DE_DISPLAY_FUNC);
> > +
> > + hwdev->mw_state = MW_START;
> > +
> > + malidp_hw_write(hwdev, fmt_id, base + MALIDP_MW_FORMAT);
> > + switch (num_planes) {
> > + case 2:
> > + malidp_hw_write(hwdev, lower_32_bits(addrs[1]), base + MALIDP_MW_P2_PTR_LOW);
> > + malidp_hw_write(hwdev, upper_32_bits(addrs[1]), base + MALIDP_MW_P2_PTR_HIGH);
> > + malidp_hw_write(hwdev, pitches[1], base + MALIDP_MW_P2_STRIDE);
> > + /* fall through */
> > + case 1:
> > + malidp_hw_write(hwdev, lower_32_bits(addrs[0]), base + MALIDP_MW_P1_PTR_LOW);
> > + malidp_hw_write(hwdev, upper_32_bits(addrs[0]), base + MALIDP_MW_P1_PTR_HIGH);
> > + malidp_hw_write(hwdev, pitches[0], base + MALIDP_MW_P1_STRIDE);
> > + break;
> > + default:
> > + WARN(1, "Invalid number of planes");
> > + }
> > +
> > + malidp_hw_write(hwdev, MALIDP_DE_H_ACTIVE(w) | MALIDP_DE_V_ACTIVE(h),
> > + MALIDP500_SE_MEMWRITE_OUT_SIZE);
> > + malidp_hw_setbits(hwdev, MALIDP_SE_MEMWRITE_EN, MALIDP500_SE_CONTROL);
> > +
> > + return 0;
> > +}
> > +
> > +static void malidp500_disable_memwrite(struct malidp_hw_device *hwdev)
> > +{
> > + u32 base = malidp_get_block_base(hwdev, MALIDP_DE_BLOCK);
> > + if (hwdev->mw_state == MW_START)
> > + hwdev->mw_state = MW_STOP;
> > + malidp_hw_clearbits(hwdev, MALIDP_SE_MEMWRITE_EN, MALIDP500_SE_CONTROL);
> > + malidp_hw_clearbits(hwdev, MALIDP_SCALE_ENGINE_EN, base + MALIDP_DE_DISPLAY_FUNC);
> > +}
> > +
> > static int malidp550_query_hw(struct malidp_hw_device *hwdev)
> > {
> > u32 conf = malidp_hw_read(hwdev, MALIDP550_CONFIG_ID);
> > @@ -598,6 +649,8 @@ static int malidp550_enable_memwrite(struct malidp_hw_device *hwdev,
> > /* enable the scaling engine block */
> > malidp_hw_setbits(hwdev, MALIDP_SCALE_ENGINE_EN, de_base + MALIDP_DE_DISPLAY_FUNC);
> >
> > + hwdev->mw_state = MW_ONESHOT;
> > +
> > malidp_hw_write(hwdev, fmt_id, base + MALIDP_MW_FORMAT);
> > switch (num_planes) {
> > case 2:
> > @@ -676,8 +729,9 @@ const struct malidp_hw malidp_device[MALIDP_MAX_DEVICES] = {
> > .vsync_irq = MALIDP500_DE_IRQ_VSYNC,
> > },
> > .se_irq_map = {
> > - .irq_mask = MALIDP500_SE_IRQ_CONF_MODE,
> > - .vsync_irq = 0,
> > + .irq_mask = MALIDP500_SE_IRQ_CONF_MODE |
> > + MALIDP500_SE_IRQ_CONF_VALID,
> > + .vsync_irq = MALIDP500_SE_IRQ_CONF_VALID,
> > },
> > .dc_irq_map = {
> > .irq_mask = MALIDP500_DE_IRQ_CONF_VALID,
> > @@ -696,6 +750,8 @@ const struct malidp_hw malidp_device[MALIDP_MAX_DEVICES] = {
> > .rotmem_required = malidp500_rotmem_required,
> > .se_set_scaling_coeffs = malidp500_se_set_scaling_coeffs,
> > .se_calc_mclk = malidp500_se_calc_mclk,
> > + .enable_memwrite = malidp500_enable_memwrite,
> > + .disable_memwrite = malidp500_disable_memwrite,
> > .features = MALIDP_DEVICE_LV_HAS_3_STRIDES,
> > },
> > [MALIDP_550] = {
> > @@ -934,7 +990,21 @@ static irqreturn_t malidp_se_irq(int irq, void *arg)
> > mask = malidp_hw_read(hwdev, hw->map.se_base + MALIDP_REG_MASKIRQ);
> > status = malidp_hw_read(hwdev, hw->map.se_base + MALIDP_REG_STATUS);
> > status &= mask;
> > - /* ToDo: status decoding and firing up of VSYNC and page flip events */
> > +
> > + if (status & se->vsync_irq) {
> > + switch (hwdev->mw_state) {
> > + case MW_STOP:
> > + case MW_ONESHOT:
> > + /* disable writeback after stop or oneshot */
> > + hwdev->mw_state = MW_NOT_ENABLED;
> > + break;
> > + case MW_START:
> > + /* writeback started, need to emulate one-shot mode */
> > + hw->disable_memwrite(hwdev);
> > + hw->set_config_valid(hwdev);
>
> Is this serialised with incoming atomic commits? We have to make sure
> we don't set CVAL while a new scene configuration is in-progress.

We are not serialised with the incoming atomic commit, and we probably
should. I'll have a think on how to sort this one out.

>
> I also think the current state tracking won't work properly for two
> subsequent frames using writeback. In enable_memwrite() you change the
> mw_state, but the currently ongoing job is relying on it to correctly
> signal. We probably need to either block incoming commits until the
> writeback is finished, or we need to enhance the state tracking to
> manage multiple commits.

I will go back to the drawing boards and come up with something more
solid.

Best regards,
Liviu

>
> Thanks,
> -Brian
>
> > + break;
> > + }
> > + }
> >
> > malidp_hw_clear_irq(hwdev, MALIDP_SE_BLOCK, status);
> >
> > @@ -964,6 +1034,7 @@ int malidp_se_irq_init(struct drm_device *drm, int irq)
> > return ret;
> > }
> >
> > + hwdev->mw_state = MW_NOT_ENABLED;
> > malidp_hw_enable_irq(hwdev, MALIDP_SE_BLOCK,
> > hwdev->hw->map.se_irq_map.irq_mask);
> >
> > diff --git a/drivers/gpu/drm/arm/malidp_hw.h b/drivers/gpu/drm/arm/malidp_hw.h
> > index a242e97cf6428..c479738b81af5 100644
> > --- a/drivers/gpu/drm/arm/malidp_hw.h
> > +++ b/drivers/gpu/drm/arm/malidp_hw.h
> > @@ -178,7 +178,7 @@ struct malidp_hw {
> > long (*se_calc_mclk)(struct malidp_hw_device *hwdev,
> > struct malidp_se_config *se_config,
> > struct videomode *vm);
> > - /**
> > + /*
> > * Enable writing to memory the content of the next frame
> > * @param hwdev - malidp_hw_device structure containing the HW description
> > * @param addrs - array of addresses for each plane
> > @@ -232,6 +232,9 @@ struct malidp_hw_device {
> > /* track the device PM state */
> > bool pm_suspended;
> >
> > + /* track the SE memory writeback state */
> > + u8 mw_state;
> > +
> > /* size of memory used for rotating layers, up to two banks available */
> > u32 rotation_memory[2];
> > };
> > diff --git a/drivers/gpu/drm/arm/malidp_regs.h b/drivers/gpu/drm/arm/malidp_regs.h
> > index e2b2c496225e3..93b198f3af864 100644
> > --- a/drivers/gpu/drm/arm/malidp_regs.h
> > +++ b/drivers/gpu/drm/arm/malidp_regs.h
> > @@ -198,7 +198,8 @@
> > #define MALIDP500_DE_LG2_PTR_BASE 0x0031c
> > #define MALIDP500_SE_BASE 0x00c00
> > #define MALIDP500_SE_CONTROL 0x00c0c
> > -#define MALIDP500_SE_PTR_BASE 0x00e0c
> > +#define MALIDP500_SE_MEMWRITE_OUT_SIZE 0x00c2c
> > +#define MALIDP500_SE_MEMWRITE_BASE 0x00e00
> > #define MALIDP500_DC_IRQ_BASE 0x00f00
> > #define MALIDP500_CONFIG_VALID 0x00f00
> > #define MALIDP500_CONFIG_ID 0x00fd4
> > --
> > 2.17.0
> >

--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯

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