Re: [PATCH v3 18/20] drm/vc4: tests: Fail the current test if we access a register

["Maíra Canal" <mcanal@igalia.com>]

On 12/1/22 12:11, Maxime Ripard wrote:
> Accessing a register when running under kunit is a bad idea since our
> device is completely mocked.
> 
> Fail the current test if we ever access any of our hardware registers.
> 
> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Reviewed-by: Maíra Canal <mcanal@igalia.com>

Just a small nit: I believe that macros with multiple statements should 
be enclosed in a do-while block [1], even READ macros. I saw that you 
enclosed the WRITE macros on a do-while block, but not the READ macros.

[1] 
https://www.kernel.org/doc/html/latest/process/coding-style.html#macros-enums-and-rtl

Best Regards,
- Maíra Canal

> ---
>   drivers/gpu/drm/vc4/vc4_crtc.c      | 13 +++++++++++--
>   drivers/gpu/drm/vc4/vc4_dpi.c       | 13 +++++++++++--
>   drivers/gpu/drm/vc4/vc4_drv.h       | 29 +++++++++++++++++++++++++----
>   drivers/gpu/drm/vc4/vc4_dsi.c       |  9 ++++++++-
>   drivers/gpu/drm/vc4/vc4_hdmi_regs.h |  4 ++++
>   drivers/gpu/drm/vc4/vc4_txp.c       | 13 +++++++++++--
>   drivers/gpu/drm/vc4/vc4_vec.c       | 13 +++++++++++--
>   7 files changed, 81 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c
> index 7d1a696477ce..a1a3465948c4 100644
> --- a/drivers/gpu/drm/vc4/vc4_crtc.c
> +++ b/drivers/gpu/drm/vc4/vc4_crtc.c
> @@ -50,8 +50,17 @@
>   
>   #define HVS_FIFO_LATENCY_PIX	6
>   
> -#define CRTC_WRITE(offset, val) writel(val, vc4_crtc->regs + (offset))
> -#define CRTC_READ(offset) readl(vc4_crtc->regs + (offset))
> +#define CRTC_WRITE(offset, val)								\
> +	do {										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		writel(val, vc4_crtc->regs + (offset));					\
> +	} while (0)
> +
> +#define CRTC_READ(offset)								\
> +	({										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		readl(vc4_crtc->regs + (offset));					\
> +	})
>   
>   static const struct debugfs_reg32 crtc_regs[] = {
>   	VC4_REG32(PV_CONTROL),
> diff --git a/drivers/gpu/drm/vc4/vc4_dpi.c b/drivers/gpu/drm/vc4/vc4_dpi.c
> index 1f8f44b7b5a5..0edf3c4c98c8 100644
> --- a/drivers/gpu/drm/vc4/vc4_dpi.c
> +++ b/drivers/gpu/drm/vc4/vc4_dpi.c
> @@ -103,8 +103,17 @@ to_vc4_dpi(struct drm_encoder *encoder)
>   	return container_of(encoder, struct vc4_dpi, encoder.base);
>   }
>   
> -#define DPI_READ(offset) readl(dpi->regs + (offset))
> -#define DPI_WRITE(offset, val) writel(val, dpi->regs + (offset))
> +#define DPI_READ(offset)								\
> +	({										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		readl(dpi->regs + (offset));						\
> +	})
> +
> +#define DPI_WRITE(offset, val)								\
> +	do {										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		writel(val, dpi->regs + (offset));					\
> +	} while (0)
>   
>   static const struct debugfs_reg32 dpi_regs[] = {
>   	VC4_REG32(DPI_C),
> diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> index 418f4f308e36..78fda5332cb3 100644
> --- a/drivers/gpu/drm/vc4/vc4_drv.h
> +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> @@ -19,6 +19,8 @@
>   #include <drm/drm_mm.h>
>   #include <drm/drm_modeset_lock.h>
>   
> +#include <kunit/test-bug.h>
> +
>   #include "uapi/drm/vc4_drm.h"
>   
>   struct drm_device;
> @@ -645,10 +647,29 @@ to_vc4_crtc_state(const struct drm_crtc_state *crtc_state)
>   	return container_of(crtc_state, struct vc4_crtc_state, base);
>   }
>   
> -#define V3D_READ(offset) readl(vc4->v3d->regs + offset)
> -#define V3D_WRITE(offset, val) writel(val, vc4->v3d->regs + offset)
> -#define HVS_READ(offset) readl(hvs->regs + offset)
> -#define HVS_WRITE(offset, val) writel(val, hvs->regs + offset)
> +#define V3D_READ(offset)								\
> +	({										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		readl(vc4->v3d->regs + (offset));						\
> +	})
> +
> +#define V3D_WRITE(offset, val)								\
> +	do {										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		writel(val, vc4->v3d->regs + (offset));					\
> +	} while (0)
> +
> +#define HVS_READ(offset)								\
> +	({										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		readl(hvs->regs + (offset));						\
> +	})
> +
> +#define HVS_WRITE(offset, val)								\
> +	do {										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		writel(val, hvs->regs + (offset));					\
> +	} while (0)
>   
>   #define VC4_REG32(reg) { .name = #reg, .offset = reg }
>   
> diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
> index 878e05d79e81..2c9cb27903a0 100644
> --- a/drivers/gpu/drm/vc4/vc4_dsi.c
> +++ b/drivers/gpu/drm/vc4/vc4_dsi.c
> @@ -617,6 +617,8 @@ dsi_dma_workaround_write(struct vc4_dsi *dsi, u32 offset, u32 val)
>   	dma_cookie_t cookie;
>   	int ret;
>   
> +	kunit_fail_current_test("Accessing a register in a unit test!\n");
> +
>   	/* DSI0 should be able to write normally. */
>   	if (!chan) {
>   		writel(val, dsi->regs + offset);
> @@ -645,7 +647,12 @@ dsi_dma_workaround_write(struct vc4_dsi *dsi, u32 offset, u32 val)
>   		DRM_ERROR("Failed to wait for DMA: %d\n", ret);
>   }
>   
> -#define DSI_READ(offset) readl(dsi->regs + (offset))
> +#define DSI_READ(offset)								\
> +	({										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		readl(dsi->regs + (offset));						\
> +	})
> +
>   #define DSI_WRITE(offset, val) dsi_dma_workaround_write(dsi, offset, val)
>   #define DSI_PORT_READ(offset) \
>   	DSI_READ(dsi->variant->port ? DSI1_##offset : DSI0_##offset)
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi_regs.h b/drivers/gpu/drm/vc4/vc4_hdmi_regs.h
> index 48db438550b1..b04b2fc8d831 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi_regs.h
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi_regs.h
> @@ -456,6 +456,8 @@ static inline u32 vc4_hdmi_read(struct vc4_hdmi *hdmi,
>   
>   	WARN_ON(pm_runtime_status_suspended(&hdmi->pdev->dev));
>   
> +	kunit_fail_current_test("Accessing an HDMI register in a unit test!\n");
> +
>   	if (reg >= variant->num_registers) {
>   		dev_warn(&hdmi->pdev->dev,
>   			 "Invalid register ID %u\n", reg);
> @@ -486,6 +488,8 @@ static inline void vc4_hdmi_write(struct vc4_hdmi *hdmi,
>   
>   	WARN_ON(pm_runtime_status_suspended(&hdmi->pdev->dev));
>   
> +	kunit_fail_current_test("Accessing an HDMI register in a unit test!\n");
> +
>   	if (reg >= variant->num_registers) {
>   		dev_warn(&hdmi->pdev->dev,
>   			 "Invalid register ID %u\n", reg);
> diff --git a/drivers/gpu/drm/vc4/vc4_txp.c b/drivers/gpu/drm/vc4/vc4_txp.c
> index 2b69454b8534..ef5cab2a3aa9 100644
> --- a/drivers/gpu/drm/vc4/vc4_txp.c
> +++ b/drivers/gpu/drm/vc4/vc4_txp.c
> @@ -145,8 +145,17 @@
>   /* Number of lines received and committed to memory. */
>   #define TXP_PROGRESS		0x10
>   
> -#define TXP_READ(offset) readl(txp->regs + (offset))
> -#define TXP_WRITE(offset, val) writel(val, txp->regs + (offset))
> +#define TXP_READ(offset)								\
> +	({										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		readl(txp->regs + (offset));						\
> +	})
> +
> +#define TXP_WRITE(offset, val)								\
> +	do {										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		writel(val, txp->regs + (offset));					\
> +	} while (0)
>   
>   struct vc4_txp {
>   	struct vc4_crtc	base;
> diff --git a/drivers/gpu/drm/vc4/vc4_vec.c b/drivers/gpu/drm/vc4/vc4_vec.c
> index e270a4099be3..f589ab918f4d 100644
> --- a/drivers/gpu/drm/vc4/vc4_vec.c
> +++ b/drivers/gpu/drm/vc4/vc4_vec.c
> @@ -207,8 +207,17 @@ struct vc4_vec {
>   	struct debugfs_regset32 regset;
>   };
>   
> -#define VEC_READ(offset) readl(vec->regs + (offset))
> -#define VEC_WRITE(offset, val) writel(val, vec->regs + (offset))
> +#define VEC_READ(offset)								\
> +	({										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		readl(vec->regs + (offset));						\
> +	})
> +
> +#define VEC_WRITE(offset, val)								\
> +	do {										\
> +		kunit_fail_current_test("Accessing a register in a unit test!\n");	\
> +		writel(val, vec->regs + (offset));					\
> +	} while (0)
>   
>   static inline struct vc4_vec *
>   encoder_to_vc4_vec(struct drm_encoder *encoder)
>