Re: [PATCH v2 2/6] media: mali-c55: Initialize the ISP in enable_streams()
From: Jacopo Mondi
Date: Fri Mar 13 2026 - 12:13:38 EST
Hi Dan
On Fri, Mar 13, 2026 at 03:59:22PM +0000, Dan Scally wrote:
> Hi Jacopo - thanks for the patches
>
> On 13/03/2026 14:53, Jacopo Mondi wrote:
> > The Mali C55 driver initializes the ISP in two points:
> >
> > 1) At probe time it disables ISP blocks by configuring them in bypass
> > mode
> > 2) At enable_streams() it initializes the crop rectangles and the image
> > processing pipeline using the current image format
> >
> > However, as ISP blocks are configured by userspace, if their
> > configuration is not reset, from the second enable_streams() call
> > onwards the ISP configuration will depend on the previous streaming
> > session configuration.
> >
> > To re-initialize the ISP completely at enable_strems() time consolidate
>
> s/enable_strems/enable_streams
>
> > the ISP block bypass configuration and the image processing path
> > configuration in a single function to be called at enabled_streams()
> > time.
>
> I'm slightly confused; the change seems fine, but as far as I can see it's
> non-functional...or is this just preliminary reorganisation to make the next
> patch easier?
Isn't mali_c55_init_context() only called at probe() time ?
IOW all the bypass configuration that were only performed at probe
time are now performed at every streaming start.
Or have I missed something ?
Thanks
j
>
> Thanks
> Dan
>
> > Cc: stable@xxxxxxxxxxxxxxx
> > Fixes: d5f281f3dd29 ("media: mali-c55: Add Mali-C55 ISP driver")
> > Signed-off-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>
> > ---
> > .../media/platform/arm/mali-c55/mali-c55-common.h | 2 +
> > .../media/platform/arm/mali-c55/mali-c55-core.c | 35 -----------
> > drivers/media/platform/arm/mali-c55/mali-c55-isp.c | 37 ++---------
> > .../media/platform/arm/mali-c55/mali-c55-params.c | 72 ++++++++++++++++++++++
> > 4 files changed, 79 insertions(+), 67 deletions(-)
> >
> > diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-common.h b/drivers/media/platform/arm/mali-c55/mali-c55-common.h
> > index 31c1deaca146..13a3e9dc4243 100644
> > --- a/drivers/media/platform/arm/mali-c55/mali-c55-common.h
> > +++ b/drivers/media/platform/arm/mali-c55/mali-c55-common.h
> > @@ -306,5 +306,7 @@ bool mali_c55_pipeline_ready(struct mali_c55 *mali_c55);
> > void mali_c55_stats_fill_buffer(struct mali_c55 *mali_c55,
> > enum mali_c55_config_spaces cfg_space);
> > void mali_c55_params_write_config(struct mali_c55 *mali_c55);
> > +void mali_c55_params_init_isp_config(struct mali_c55 *mali_c55,
> > + const struct v4l2_subdev_state *state);
> > #endif /* _MALI_C55_COMMON_H */
> > diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-core.c b/drivers/media/platform/arm/mali-c55/mali-c55-core.c
> > index 43b834459ccf..c1a562cd214e 100644
> > --- a/drivers/media/platform/arm/mali-c55/mali-c55-core.c
> > +++ b/drivers/media/platform/arm/mali-c55/mali-c55-core.c
> > @@ -663,41 +663,6 @@ static int mali_c55_init_context(struct mali_c55 *mali_c55,
> > mali_c55->base + config_space_addrs[MALI_C55_CONFIG_PING],
> > MALI_C55_CONFIG_SPACE_SIZE);
> > - /*
> > - * Some features of the ISP need to be disabled by default and only
> > - * enabled at the same time as they're configured by a parameters buffer
> > - */
> > -
> > - /* Bypass the sqrt and square compression and expansion modules */
> > - mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_BYPASS_1,
> > - MALI_C55_REG_BYPASS_1_FE_SQRT,
> > - MALI_C55_REG_BYPASS_1_FE_SQRT);
> > - mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_BYPASS_3,
> > - MALI_C55_REG_BYPASS_3_SQUARE_BE,
> > - MALI_C55_REG_BYPASS_3_SQUARE_BE);
> > -
> > - /* Bypass the temper module */
> > - mali_c55_ctx_write(mali_c55, MALI_C55_REG_BYPASS_2,
> > - MALI_C55_REG_BYPASS_2_TEMPER);
> > -
> > - /* Disable the temper module's DMA read/write */
> > - mali_c55_ctx_write(mali_c55, MALI_C55_REG_TEMPER_DMA_IO, 0x0);
> > -
> > - /* Bypass the colour noise reduction */
> > - mali_c55_ctx_write(mali_c55, MALI_C55_REG_BYPASS_4,
> > - MALI_C55_REG_BYPASS_4_CNR);
> > -
> > - /* Disable the sinter module */
> > - mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_SINTER_CONFIG,
> > - MALI_C55_SINTER_ENABLE_MASK, 0);
> > -
> > - /* Disable the RGB Gamma module for each output */
> > - mali_c55_ctx_write(mali_c55, MALI_C55_REG_FR_GAMMA_RGB_ENABLE, 0);
> > - mali_c55_ctx_write(mali_c55, MALI_C55_REG_DS_GAMMA_RGB_ENABLE, 0);
> > -
> > - /* Disable the colour correction matrix */
> > - mali_c55_ctx_write(mali_c55, MALI_C55_REG_CCM_ENABLE, 0);
> > -
> > return 0;
> > }
> > diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-isp.c b/drivers/media/platform/arm/mali-c55/mali-c55-isp.c
> > index 497f25fbdd13..4c0fd1ec741c 100644
> > --- a/drivers/media/platform/arm/mali-c55/mali-c55-isp.c
> > +++ b/drivers/media/platform/arm/mali-c55/mali-c55-isp.c
> > @@ -112,9 +112,6 @@ static int mali_c55_isp_start(struct mali_c55 *mali_c55,
> > const struct v4l2_subdev_state *state)
> > {
> > struct mali_c55_context *ctx = mali_c55_get_active_context(mali_c55);
> > - const struct mali_c55_isp_format_info *cfg;
> > - const struct v4l2_mbus_framefmt *format;
> > - const struct v4l2_rect *crop;
> > u32 val;
> > int ret;
> > @@ -122,35 +119,11 @@ static int mali_c55_isp_start(struct mali_c55 *mali_c55,
> > MALI_C55_REG_MCU_CONFIG_WRITE_MASK,
> > MALI_C55_REG_MCU_CONFIG_WRITE_PING);
> > - /* Apply input windowing */
> > - crop = v4l2_subdev_state_get_crop(state, MALI_C55_ISP_PAD_SINK_VIDEO);
> > - format = v4l2_subdev_state_get_format(state,
> > - MALI_C55_ISP_PAD_SINK_VIDEO);
> > - cfg = mali_c55_isp_get_mbus_config_by_code(format->code);
> > -
> > - mali_c55_write(mali_c55, MALI_C55_REG_HC_START,
> > - MALI_C55_HC_START(crop->left));
> > - mali_c55_write(mali_c55, MALI_C55_REG_HC_SIZE,
> > - MALI_C55_HC_SIZE(crop->width));
> > - mali_c55_write(mali_c55, MALI_C55_REG_VC_START_SIZE,
> > - MALI_C55_VC_START(crop->top) |
> > - MALI_C55_VC_SIZE(crop->height));
> > - mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_BASE_ADDR,
> > - MALI_C55_REG_ACTIVE_WIDTH_MASK, format->width);
> > - mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_BASE_ADDR,
> > - MALI_C55_REG_ACTIVE_HEIGHT_MASK,
> > - format->height << 16);
> > - mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_BAYER_ORDER,
> > - MALI_C55_BAYER_ORDER_MASK, cfg->order);
> > - mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_INPUT_WIDTH,
> > - MALI_C55_INPUT_WIDTH_MASK,
> > - MALI_C55_INPUT_WIDTH_20BIT);
> > -
> > - mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_ISP_RAW_BYPASS,
> > - MALI_C55_ISP_RAW_BYPASS_BYPASS_MASK,
> > - cfg->bypass ? MALI_C55_ISP_RAW_BYPASS_BYPASS_MASK :
> > - 0x00);
> > -
> > + /*
> > + * Apply default ISP configuration and the apply configurations from
> > + * the first available parameters buffer.
> > + */
> > + mali_c55_params_init_isp_config(mali_c55, state);
> > mali_c55_params_write_config(mali_c55);
> > ret = mali_c55_config_write(ctx, MALI_C55_CONFIG_PING, true);
> > if (ret) {
> > diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-params.c b/drivers/media/platform/arm/mali-c55/mali-c55-params.c
> > index c03a6120ddbf..c84a6047a570 100644
> > --- a/drivers/media/platform/arm/mali-c55/mali-c55-params.c
> > +++ b/drivers/media/platform/arm/mali-c55/mali-c55-params.c
> > @@ -732,6 +732,78 @@ void mali_c55_params_write_config(struct mali_c55 *mali_c55)
> > vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_DONE);
> > }
> > +void mali_c55_params_init_isp_config(struct mali_c55 *mali_c55,
> > + const struct v4l2_subdev_state *state)
> > +{
> > + const struct mali_c55_isp_format_info *cfg;
> > + const struct v4l2_mbus_framefmt *format;
> > + const struct v4l2_rect *crop;
> > +
> > + /* Apply input windowing */
> > + crop = v4l2_subdev_state_get_crop(state, MALI_C55_ISP_PAD_SINK_VIDEO);
> > + format = v4l2_subdev_state_get_format(state,
> > + MALI_C55_ISP_PAD_SINK_VIDEO);
> > + cfg = mali_c55_isp_get_mbus_config_by_code(format->code);
> > +
> > + mali_c55_write(mali_c55, MALI_C55_REG_HC_START,
> > + MALI_C55_HC_START(crop->left));
> > + mali_c55_write(mali_c55, MALI_C55_REG_HC_SIZE,
> > + MALI_C55_HC_SIZE(crop->width));
> > + mali_c55_write(mali_c55, MALI_C55_REG_VC_START_SIZE,
> > + MALI_C55_VC_START(crop->top) |
> > + MALI_C55_VC_SIZE(crop->height));
> > + mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_BASE_ADDR,
> > + MALI_C55_REG_ACTIVE_WIDTH_MASK, format->width);
> > + mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_BASE_ADDR,
> > + MALI_C55_REG_ACTIVE_HEIGHT_MASK,
> > + format->height << 16);
> > + mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_BAYER_ORDER,
> > + MALI_C55_BAYER_ORDER_MASK, cfg->order);
> > + mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_INPUT_WIDTH,
> > + MALI_C55_INPUT_WIDTH_MASK,
> > + MALI_C55_INPUT_WIDTH_20BIT);
> > +
> > + mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_ISP_RAW_BYPASS,
> > + MALI_C55_ISP_RAW_BYPASS_BYPASS_MASK,
> > + cfg->bypass ? MALI_C55_ISP_RAW_BYPASS_BYPASS_MASK :
> > + 0x00);
> > +
> > + /*
> > + * Some features of the ISP need to be disabled by default and only
> > + * enabled at the same time as they're configured by a parameters buffer
> > + */
> > +
> > + /* Bypass the sqrt and square compression and expansion modules */
> > + mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_BYPASS_1,
> > + MALI_C55_REG_BYPASS_1_FE_SQRT,
> > + MALI_C55_REG_BYPASS_1_FE_SQRT);
> > + mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_BYPASS_3,
> > + MALI_C55_REG_BYPASS_3_SQUARE_BE,
> > + MALI_C55_REG_BYPASS_3_SQUARE_BE);
> > +
> > + /* Bypass the temper module */
> > + mali_c55_ctx_write(mali_c55, MALI_C55_REG_BYPASS_2,
> > + MALI_C55_REG_BYPASS_2_TEMPER);
> > +
> > + /* Disable the temper module's DMA read/write */
> > + mali_c55_ctx_write(mali_c55, MALI_C55_REG_TEMPER_DMA_IO, 0x0);
> > +
> > + /* Bypass the colour noise reduction */
> > + mali_c55_ctx_write(mali_c55, MALI_C55_REG_BYPASS_4,
> > + MALI_C55_REG_BYPASS_4_CNR);
> > +
> > + /* Disable the sinter module */
> > + mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_SINTER_CONFIG,
> > + MALI_C55_SINTER_ENABLE_MASK, 0);
> > +
> > + /* Disable the RGB Gamma module for each output */
> > + mali_c55_ctx_write(mali_c55, MALI_C55_REG_FR_GAMMA_RGB_ENABLE, 0);
> > + mali_c55_ctx_write(mali_c55, MALI_C55_REG_DS_GAMMA_RGB_ENABLE, 0);
> > +
> > + /* Disable the colour correction matrix */
> > + mali_c55_ctx_write(mali_c55, MALI_C55_REG_CCM_ENABLE, 0);
> > +}
> > +
> > void mali_c55_unregister_params(struct mali_c55 *mali_c55)
> > {
> > struct mali_c55_params *params = &mali_c55->params;
> >
>