On Sat, 09 Nov 2013, Shobhit Kumar <shobhit.kumar@xxxxxxxxx> wrote:
> Pixel clock based calculation is recommended in the MIPI host controller
> documentation
>
> v2: Based on review comments from Jani and Ville
> - Use dsi_clk in KHz rather than converting in Hz and back to MHz
> - RR formula is retained though not used but return dsi_clk in KHz now
> - Moved the m-n-p changes into a separate patch
> - Removed the parameter check for intel_dsi->dsi_clock_freq. This will be
> bought back in if needed when appropriate panel drivers are done
>
> Signed-off-by: Vijayakumar Balakrishnan <vijayakumar.balakrishnan@xxxxxxxxx>
> Signed-off-by: Shobhit Kumar <shobhit.kumar@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_dsi_pll.c | 46 +++++++++++++++++++++++++++++-----
> 1 file changed, 40 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dsi_pll.c b/drivers/gpu/drm/i915/intel_dsi_pll.c
> index 44279b2..9f3e6b0 100644
> --- a/drivers/gpu/drm/i915/intel_dsi_pll.c
> +++ b/drivers/gpu/drm/i915/intel_dsi_pll.c
> @@ -50,6 +50,8 @@ static const u32 lfsr_converts[] = {
> 71, 35 /* 91 - 92 */
> };
>
> +#ifdef DSI_CLK_FROM_RR
> +
> static u32 dsi_rr_formula(const struct drm_display_mode *mode,
> int pixel_format, int video_mode_format,
> int lane_count, bool eotp)
> @@ -121,7 +123,7 @@ static u32 dsi_rr_formula(const struct drm_display_mode *mode,
>
> /* the dsi clock is divided by 2 in the hardware to get dsi ddr clock */
> dsi_bit_clock_hz = bytes_per_x_frames_x_lanes * 8;
> - dsi_clk = dsi_bit_clock_hz / (1000 * 1000);
> + dsi_clk = dsi_bit_clock_hz / 1000;
>
> if (eotp && video_mode_format == VIDEO_MODE_BURST)
> dsi_clk *= 2;
> @@ -129,6 +131,38 @@ static u32 dsi_rr_formula(const struct drm_display_mode *mode,
> return dsi_clk;
> }
>
> +#else
> +
> +/* Get DSI clock from pixel clock */
> +static u32 dsi_clk_from_pclk(const struct drm_display_mode *mode,
> + int pixel_format, int lane_count)
> +{
> + u32 dsi_clk_khz;
> + u32 bpp;
> +
> + switch (pixel_format) {
> + default:
> + case VID_MODE_FORMAT_RGB888:
> + case VID_MODE_FORMAT_RGB666_LOOSE:
> + bpp = 24;
> + break;
> + case VID_MODE_FORMAT_RGB666:
> + bpp = 18;
> + break;
> + case VID_MODE_FORMAT_RGB565:
> + bpp = 16;
> + break;
> + }
> +
> + /* DSI data rate = pixel clock * bits per pixel / lane count
> + pixel clock is converted from KHz to Hz */
> + dsi_clk_khz = DIV_ROUND_CLOSEST(mode->clock * bpp, lane_count);
> +
> + return dsi_clk_khz;
> +}
> +
> +#endif
> +
> #ifdef MNP_FROM_TABLE
>
> struct dsi_clock_table {
> @@ -200,13 +234,14 @@ static int dsi_calc_mnp(u32 dsi_clk, struct dsi_mnp *dsi_mnp)
> u32 calc_p;
> u32 m_seed;
>
> - if (dsi_clk < 300 || dsi_clk > 1150) {
> + /* dsi_clk is expected in KHZ */
> + if (dsi_clk < 300000 || dsi_clk > 1150000) {
> DRM_ERROR("DSI CLK Out of Range\n");
> return -ECHRNG;
> }
>
> ref_clk = 25000;
> - target_dsi_clk = dsi_clk * 1000;
> + target_dsi_clk = dsi_clk;
The *other* dsi_calc_mnp() (with MNP_FROM_TABLE defined) remains
unchanged, and bitrots. Either /= 1000 the input there, or better, if
you don't see that the other function will be needed, just remove it.
BR,
Jani.
> error = 0xFFFFFFFF;
> calc_m = 0;
> calc_p = 0;
> @@ -251,9 +286,8 @@ static void vlv_configure_dsi_pll(struct intel_encoder *encoder)
> struct dsi_mnp dsi_mnp;
> u32 dsi_clk;
>
> - dsi_clk = dsi_rr_formula(mode, intel_dsi->pixel_format,
> - intel_dsi->video_mode_format,
> - intel_dsi->lane_count, !intel_dsi->eot_disable);
> + dsi_clk = dsi_clk_from_pclk(mode, intel_dsi->pixel_format,
> + intel_dsi->lane_count);
>
> ret = dsi_calc_mnp(dsi_clk, &dsi_mnp);
> if (ret) {
> --
> 1.7.9.5
>
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--
Jani Nikula, Intel Open Source Technology Center
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