drivers/gpu/drm/radeon/evergreen.c

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/radeon/evergreen.c

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/radeon/evergreen.c
Extension
.c
Size
165686 bytes
Lines
5547
Domain
Driver Families
Bucket
drivers/gpu
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct evergreen_wm_params {
	u32 dram_channels; /* number of dram channels */
	u32 yclk;          /* bandwidth per dram data pin in kHz */
	u32 sclk;          /* engine clock in kHz */
	u32 disp_clk;      /* display clock in kHz */
	u32 src_width;     /* viewport width */
	u32 active_time;   /* active display time in ns */
	u32 blank_time;    /* blank time in ns */
	bool interlaced;    /* mode is interlaced */
	fixed20_12 vsc;    /* vertical scale ratio */
	u32 num_heads;     /* number of active crtcs */
	u32 bytes_per_pixel; /* bytes per pixel display + overlay */
	u32 lb_size;       /* line buffer allocated to pipe */
	u32 vtaps;         /* vertical scaler taps */
};

static u32 evergreen_dram_bandwidth(struct evergreen_wm_params *wm)
{
	/* Calculate DRAM Bandwidth and the part allocated to display. */
	fixed20_12 dram_efficiency; /* 0.7 */
	fixed20_12 yclk, dram_channels, bandwidth;
	fixed20_12 a;

	a.full = dfixed_const(1000);
	yclk.full = dfixed_const(wm->yclk);
	yclk.full = dfixed_div(yclk, a);
	dram_channels.full = dfixed_const(wm->dram_channels * 4);
	a.full = dfixed_const(10);
	dram_efficiency.full = dfixed_const(7);
	dram_efficiency.full = dfixed_div(dram_efficiency, a);
	bandwidth.full = dfixed_mul(dram_channels, yclk);
	bandwidth.full = dfixed_mul(bandwidth, dram_efficiency);

	return dfixed_trunc(bandwidth);
}

static u32 evergreen_dram_bandwidth_for_display(struct evergreen_wm_params *wm)
{
	/* Calculate DRAM Bandwidth and the part allocated to display. */
	fixed20_12 disp_dram_allocation; /* 0.3 to 0.7 */
	fixed20_12 yclk, dram_channels, bandwidth;
	fixed20_12 a;

	a.full = dfixed_const(1000);
	yclk.full = dfixed_const(wm->yclk);
	yclk.full = dfixed_div(yclk, a);
	dram_channels.full = dfixed_const(wm->dram_channels * 4);
	a.full = dfixed_const(10);
	disp_dram_allocation.full = dfixed_const(3); /* XXX worse case value 0.3 */
	disp_dram_allocation.full = dfixed_div(disp_dram_allocation, a);
	bandwidth.full = dfixed_mul(dram_channels, yclk);
	bandwidth.full = dfixed_mul(bandwidth, disp_dram_allocation);

	return dfixed_trunc(bandwidth);
}

static u32 evergreen_data_return_bandwidth(struct evergreen_wm_params *wm)
{
	/* Calculate the display Data return Bandwidth */
	fixed20_12 return_efficiency; /* 0.8 */
	fixed20_12 sclk, bandwidth;
	fixed20_12 a;

	a.full = dfixed_const(1000);
	sclk.full = dfixed_const(wm->sclk);
	sclk.full = dfixed_div(sclk, a);
	a.full = dfixed_const(10);
	return_efficiency.full = dfixed_const(8);
	return_efficiency.full = dfixed_div(return_efficiency, a);
	a.full = dfixed_const(32);
	bandwidth.full = dfixed_mul(a, sclk);
	bandwidth.full = dfixed_mul(bandwidth, return_efficiency);

	return dfixed_trunc(bandwidth);
}

static u32 evergreen_dmif_request_bandwidth(struct evergreen_wm_params *wm)
{
	/* Calculate the DMIF Request Bandwidth */
	fixed20_12 disp_clk_request_efficiency; /* 0.8 */
	fixed20_12 disp_clk, bandwidth;
	fixed20_12 a;

	a.full = dfixed_const(1000);
	disp_clk.full = dfixed_const(wm->disp_clk);
	disp_clk.full = dfixed_div(disp_clk, a);
	a.full = dfixed_const(10);
	disp_clk_request_efficiency.full = dfixed_const(8);
	disp_clk_request_efficiency.full = dfixed_div(disp_clk_request_efficiency, a);
	a.full = dfixed_const(32);

Annotation

Implementation Notes