* [PATCH] drm: mxsfb: Implement LCDIF scanout CRC32 support
@ 2022-04-09 23:10 Marek Vasut
2022-04-11 8:42 ` Dan Carpenter
0 siblings, 1 reply; 2+ messages in thread
From: Marek Vasut @ 2022-04-09 23:10 UTC (permalink / raw)
To: dri-devel
Cc: Marek Vasut, Peng Fan, Alexander Stein, robert.foss,
Laurent Pinchart, Robby Cai, Sam Ravnborg
The LCDIF controller as present in i.MX28/i.MX6SX/i.MX8M Mini/Nano has
CRC_STAT register, which contains CRC32 of the frame as it was clocked
out of the DPI interface of the LCDIF. This is most likely meant as a
functional safety feature.
Unfortunately, there is zero documentation on how the CRC32 is calculated,
there is no documentation of the polynomial, the init value, nor on which
data is the checksum applied.
By applying brute-force on 8 pixel / 2 line frame, which is the minimum
size LCDIF would work with, it turns out the polynomial is CRC32_POLY_LE
0xedb88320 , init value is 0xffffffff , the input data are bitrev32()
of the entire frame and the resulting CRC has to be also bitrev32()ed.
Doing this calculation in kernel for each frame is unrealistic due to the
CPU demand, so attach the CRC collected from hardware to a frame instead.
The DRM subsystem already has an interface for this purpose and the CRC
can be accessed e.g. via debugfs:
"
$ echo auto > /sys/kernel/debug/dri/1/crtc-0/crc/control
$ cat /sys/kernel/debug/dri/1/crtc-0/crc/data
0x0000408c 0xa4e5cdd8
0x0000408d 0x72f537b4
"
The per-frame CRC can be used by userspace e.g. during automated testing,
to verify that whatever buffer was sent to be scanned out was actually
scanned out of the LCDIF correctly.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexander Stein <alexander.stein@ew.tq-group.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Robby Cai <robby.cai@nxp.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Stefan Agner <stefan@agner.ch>
---
drivers/gpu/drm/mxsfb/mxsfb_drv.c | 15 +++++++-
drivers/gpu/drm/mxsfb/mxsfb_drv.h | 3 ++
drivers/gpu/drm/mxsfb/mxsfb_kms.c | 59 ++++++++++++++++++++++++++++--
drivers/gpu/drm/mxsfb/mxsfb_regs.h | 1 +
4 files changed, 73 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
index 94cafff7f68d5..ccf4107476ecc 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
@@ -9,6 +9,7 @@
*/
#include <linux/clk.h>
+#include <linux/crc32.h>
#include <linux/dma-mapping.h>
#include <linux/io.h>
#include <linux/module.h>
@@ -52,6 +53,7 @@ static const struct mxsfb_devdata mxsfb_devdata[] = {
.hs_wdth_shift = 24,
.has_overlay = false,
.has_ctrl2 = false,
+ .has_crc32 = false,
},
[MXSFB_V4] = {
.transfer_count = LCDC_V4_TRANSFER_COUNT,
@@ -61,6 +63,7 @@ static const struct mxsfb_devdata mxsfb_devdata[] = {
.hs_wdth_shift = 18,
.has_overlay = false,
.has_ctrl2 = true,
+ .has_crc32 = true,
},
[MXSFB_V6] = {
.transfer_count = LCDC_V4_TRANSFER_COUNT,
@@ -70,6 +73,7 @@ static const struct mxsfb_devdata mxsfb_devdata[] = {
.hs_wdth_shift = 18,
.has_overlay = true,
.has_ctrl2 = true,
+ .has_crc32 = true,
},
};
@@ -145,12 +149,19 @@ static irqreturn_t mxsfb_irq_handler(int irq, void *data)
{
struct drm_device *drm = data;
struct mxsfb_drm_private *mxsfb = drm->dev_private;
- u32 reg;
+ u32 reg, crc;
+ u64 vbc;
reg = readl(mxsfb->base + LCDC_CTRL1);
- if (reg & CTRL1_CUR_FRAME_DONE_IRQ)
+ if (reg & CTRL1_CUR_FRAME_DONE_IRQ) {
drm_crtc_handle_vblank(&mxsfb->crtc);
+ if (mxsfb->crc_active) {
+ crc = readl(mxsfb->base + LCDC_V4_CRC_STAT);
+ vbc = drm_crtc_accurate_vblank_count(&mxsfb->crtc);
+ drm_crtc_add_crc_entry(&mxsfb->crtc, true, vbc, &crc);
+ }
+ }
writel(CTRL1_CUR_FRAME_DONE_IRQ, mxsfb->base + LCDC_CTRL1 + REG_CLR);
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.h b/drivers/gpu/drm/mxsfb/mxsfb_drv.h
index ddb5b0417a82c..d160d921b25fc 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_drv.h
+++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.h
@@ -23,6 +23,7 @@ struct mxsfb_devdata {
unsigned int hs_wdth_shift;
bool has_overlay;
bool has_ctrl2;
+ bool has_crc32;
};
struct mxsfb_drm_private {
@@ -44,6 +45,8 @@ struct mxsfb_drm_private {
struct drm_encoder encoder;
struct drm_connector *connector;
struct drm_bridge *bridge;
+
+ bool crc_active;
};
static inline struct mxsfb_drm_private *
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
index c7f14ef1edc25..85ba17fbbe35c 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -454,6 +454,39 @@ static void mxsfb_crtc_disable_vblank(struct drm_crtc *crtc)
writel(CTRL1_CUR_FRAME_DONE_IRQ, mxsfb->base + LCDC_CTRL1 + REG_CLR);
}
+static int mxsfb_crtc_set_crc_source(struct drm_crtc *crtc, const char *source)
+{
+ struct mxsfb_drm_private *mxsfb = to_mxsfb_drm_private(crtc->dev);
+
+ if (!crtc)
+ return -ENODEV;
+
+ if (source && strcmp(source, "auto") == 0)
+ mxsfb->crc_active = true;
+ else if (!source)
+ mxsfb->crc_active = false;
+ else
+ return -EINVAL;
+
+ return 0;
+}
+
+static int mxsfb_crtc_verify_crc_source(struct drm_crtc *crtc,
+ const char *source, size_t *values_cnt)
+{
+ if (!crtc)
+ return -ENODEV;
+
+ if (source && strcmp(source, "auto") != 0) {
+ DRM_DEBUG_DRIVER("Unknown CRC source %s for %s\n",
+ source, crtc->name);
+ return -EINVAL;
+ }
+
+ *values_cnt = 1;
+ return 0;
+}
+
static const struct drm_crtc_helper_funcs mxsfb_crtc_helper_funcs = {
.atomic_check = mxsfb_crtc_atomic_check,
.atomic_flush = mxsfb_crtc_atomic_flush,
@@ -472,6 +505,19 @@ static const struct drm_crtc_funcs mxsfb_crtc_funcs = {
.disable_vblank = mxsfb_crtc_disable_vblank,
};
+static const struct drm_crtc_funcs mxsfb_crtc_with_crc_funcs = {
+ .reset = drm_atomic_helper_crtc_reset,
+ .destroy = drm_crtc_cleanup,
+ .set_config = drm_atomic_helper_set_config,
+ .page_flip = drm_atomic_helper_page_flip,
+ .atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
+ .atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
+ .enable_vblank = mxsfb_crtc_enable_vblank,
+ .disable_vblank = mxsfb_crtc_disable_vblank,
+ .set_crc_source = mxsfb_crtc_set_crc_source,
+ .verify_crc_source = mxsfb_crtc_verify_crc_source,
+};
+
/* -----------------------------------------------------------------------------
* Encoder
*/
@@ -655,9 +701,16 @@ int mxsfb_kms_init(struct mxsfb_drm_private *mxsfb)
}
drm_crtc_helper_add(crtc, &mxsfb_crtc_helper_funcs);
- ret = drm_crtc_init_with_planes(mxsfb->drm, crtc,
- &mxsfb->planes.primary, NULL,
- &mxsfb_crtc_funcs, NULL);
+ if (mxsfb->devdata->has_crc32) {
+ ret = drm_crtc_init_with_planes(mxsfb->drm, crtc,
+ &mxsfb->planes.primary, NULL,
+ &mxsfb_crtc_with_crc_funcs,
+ NULL);
+ } else {
+ ret = drm_crtc_init_with_planes(mxsfb->drm, crtc,
+ &mxsfb->planes.primary, NULL,
+ &mxsfb_crtc_funcs, NULL);
+ }
if (ret)
return ret;
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_regs.h b/drivers/gpu/drm/mxsfb/mxsfb_regs.h
index 694fea13e893e..cf813a1da1d78 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_regs.h
+++ b/drivers/gpu/drm/mxsfb/mxsfb_regs.h
@@ -26,6 +26,7 @@
#define LCDC_VDCTRL2 0x90
#define LCDC_VDCTRL3 0xa0
#define LCDC_VDCTRL4 0xb0
+#define LCDC_V4_CRC_STAT 0x1a0
#define LCDC_V4_DEBUG0 0x1d0
#define LCDC_V3_DEBUG0 0x1f0
#define LCDC_AS_CTRL 0x210
--
2.35.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] drm: mxsfb: Implement LCDIF scanout CRC32 support
2022-04-09 23:10 [PATCH] drm: mxsfb: Implement LCDIF scanout CRC32 support Marek Vasut
@ 2022-04-11 8:42 ` Dan Carpenter
0 siblings, 0 replies; 2+ messages in thread
From: Dan Carpenter @ 2022-04-11 8:42 UTC (permalink / raw)
To: kbuild, Marek Vasut, dri-devel
Cc: Marek Vasut, Peng Fan, kbuild-all, lkp, Alexander Stein,
robert.foss, Laurent Pinchart, Sam Ravnborg, Robby Cai
Hi Marek,
url: https://github.com/intel-lab-lkp/linux/commits/Marek-Vasut/drm-mxsfb-Implement-LCDIF-scanout-CRC32-support/20220410-071222
base: git://anongit.freedesktop.org/drm/drm drm-next
config: i386-randconfig-m021-20220411 (https://download.01.org/0day-ci/archive/20220411/202204111055.ETeht46W-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.2.0-19) 11.2.0
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
smatch warnings:
drivers/gpu/drm/mxsfb/mxsfb_kms.c:444 mxsfb_crtc_set_crc_source() warn: variable dereferenced before check 'crtc' (see line 442)
vim +/crtc +444 drivers/gpu/drm/mxsfb/mxsfb_kms.c
5797982b2ba894 Marek Vasut 2022-04-10 440 static int mxsfb_crtc_set_crc_source(struct drm_crtc *crtc, const char *source)
5797982b2ba894 Marek Vasut 2022-04-10 441 {
5797982b2ba894 Marek Vasut 2022-04-10 @442 struct mxsfb_drm_private *mxsfb = to_mxsfb_drm_private(crtc->dev);
^^^^^^^^^
Dereference
5797982b2ba894 Marek Vasut 2022-04-10 443
5797982b2ba894 Marek Vasut 2022-04-10 @444 if (!crtc)
^^^^^
Checked too late
5797982b2ba894 Marek Vasut 2022-04-10 445 return -ENODEV;
5797982b2ba894 Marek Vasut 2022-04-10 446
5797982b2ba894 Marek Vasut 2022-04-10 447 if (source && strcmp(source, "auto") == 0)
5797982b2ba894 Marek Vasut 2022-04-10 448 mxsfb->crc_active = true;
5797982b2ba894 Marek Vasut 2022-04-10 449 else if (!source)
5797982b2ba894 Marek Vasut 2022-04-10 450 mxsfb->crc_active = false;
5797982b2ba894 Marek Vasut 2022-04-10 451 else
5797982b2ba894 Marek Vasut 2022-04-10 452 return -EINVAL;
5797982b2ba894 Marek Vasut 2022-04-10 453
5797982b2ba894 Marek Vasut 2022-04-10 454 return 0;
5797982b2ba894 Marek Vasut 2022-04-10 455 }
--
0-DAY CI Kernel Test Service
https://01.org/lkp
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