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

Maíra Canal <mcanal@xxxxxxxxxx> · Wed, 7 Dec 2022 11:26:13 -0300

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@xxxxxxxxxx>
Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx>

Reviewed-by: Maíra Canal <mcanal@xxxxxxxxxx>

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)







