Hi,
i currently try to write a LIDD version of the TILCDC driver in
driver/gpu/drm.
During my investigations I found the function "tilcdc_pm_suspend" in
tilcdc_drv.c:
#ifdef CONFIG_PM_SLEEP
static int tilcdc_pm_suspend(struct device *dev)
{
.....
/* Save register state: */
for (i = 0; i < ARRAY_SIZE(registers); i++)
if (registers[i].save && (priv->rev >= registers[i].rev))
priv->saved_register[n++] = tilcdc_read(ddev,
registers[i].reg);
priv->ctx_valid = true;
return 0;
}
The member "saved_register" that is filled with register values here is
an array defined in tilcdc_drv.h:
struct tilcdc_drm_private {
.....
/* register contents saved across suspend/resume: */
u32 saved_register[12];
bool ctx_valid;
.....
As you can see the size of that array is 12 times u32, so it can keep 12
register values.
But if you have a look at the register list to be saved, you will find:
#if defined(CONFIG_DEBUG_FS) || defined(CONFIG_PM_SLEEP)
static const struct {
const char *name;
uint8_t rev;
uint8_t save;
uint32_t reg;
} registers[] = {
#define REG(rev, save, reg) { #reg, rev, save, reg }
/* exists in revision 1: */
REG(1, false, LCDC_PID_REG),
REG(1, true, LCDC_CTRL_REG),
REG(1, false, LCDC_STAT_REG),
REG(1, true, LCDC_RASTER_CTRL_REG),
REG(1, true, LCDC_RASTER_TIMING_0_REG),
REG(1, true, LCDC_RASTER_TIMING_1_REG),
REG(1, true, LCDC_RASTER_TIMING_2_REG),
REG(1, true, LCDC_DMA_CTRL_REG),
REG(1, true, LCDC_DMA_FB_BASE_ADDR_0_REG),
REG(1, true, LCDC_DMA_FB_CEILING_ADDR_0_REG),
REG(1, true, LCDC_DMA_FB_BASE_ADDR_1_REG),
REG(1, true, LCDC_DMA_FB_CEILING_ADDR_1_REG),
/* new in revision 2: */
REG(2, false, LCDC_RAW_STAT_REG),
REG(2, false, LCDC_MASKED_STAT_REG),
REG(2, false, LCDC_INT_ENABLE_SET_REG),
REG(2, false, LCDC_INT_ENABLE_CLR_REG),
REG(2, false, LCDC_END_OF_INT_IND_REG),
REG(2, true, LCDC_CLK_ENABLE_REG),
REG(2, true, LCDC_INT_ENABLE_SET_REG),
#undef REG
};
#endif
And if I count correctly in case you have an LCDC Revision 2, there will
be 19 registers saved to the array.
So probably you will write over the end of that array.
I hope the form of my post fits the posting rules of this forum. If not,
sorry. It is my very first post!
Br,
Michael
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