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