drm/msm/dsi: add a helper method to compute the dsi byte clk

Re-arrange the dsi_calc_pclk method to two helpers, one to
compute the DSI byte clk and the other to compute the pclk.

This makes the separation of the two clean and also allows
clients to compute and use the dsi byte clk separately.

changes in v2:
	- move the assignments to definition lines
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/518005/
Link: https://lore.kernel.org/r/20230112001600.12791-1-quic_abhinavk@quicinc.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/dsi/dsi.h

@@ -118,6 +118,8 @@ int dsi_link_clk_enable_6g(struct msm_dsi_host *msm_host);
 int dsi_link_clk_enable_v2(struct msm_dsi_host *msm_host);
 void dsi_link_clk_disable_6g(struct msm_dsi_host *msm_host);
 void dsi_link_clk_disable_v2(struct msm_dsi_host *msm_host);
+unsigned long dsi_byte_clk_get_rate(struct mipi_dsi_host *host, bool is_bonded_dsi,
+				    const struct drm_display_mode *mode);
 int dsi_tx_buf_alloc_6g(struct msm_dsi_host *msm_host, int size);
 int dsi_tx_buf_alloc_v2(struct msm_dsi_host *msm_host, int size);
 void *dsi_tx_buf_get_6g(struct msm_dsi_host *msm_host);

drivers/gpu/drm/msm/dsi/dsi_host.c

@@ -570,9 +570,8 @@ void dsi_link_clk_disable_v2(struct msm_dsi_host *msm_host)
 	clk_disable_unprepare(msm_host->byte_clk);
 }
 
-static unsigned long dsi_get_pclk_rate(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
+static unsigned long dsi_get_pclk_rate(const struct drm_display_mode *mode, bool is_bonded_dsi)
 {
-	struct drm_display_mode *mode = msm_host->mode;
 	unsigned long pclk_rate;
 
 	pclk_rate = mode->clock * 1000;
@@ -589,11 +588,13 @@ static unsigned long dsi_get_pclk_rate(struct msm_dsi_host *msm_host, bool is_bo
 	return pclk_rate;
 }
 
-static void dsi_calc_pclk(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
+unsigned long dsi_byte_clk_get_rate(struct mipi_dsi_host *host, bool is_bonded_dsi,
+				    const struct drm_display_mode *mode)
 {
+	struct msm_dsi_host *msm_host = to_msm_dsi_host(host);
 	u8 lanes = msm_host->lanes;
 	u32 bpp = dsi_get_bpp(msm_host->format);
-	unsigned long pclk_rate = dsi_get_pclk_rate(msm_host, is_bonded_dsi);
+	unsigned long pclk_rate = dsi_get_pclk_rate(mode, is_bonded_dsi);
 	u64 pclk_bpp = (u64)pclk_rate * bpp;
 
 	if (lanes == 0) {
@@ -607,8 +608,14 @@ static void dsi_calc_pclk(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
 	else
 		do_div(pclk_bpp, (8 * lanes));
 
-	msm_host->pixel_clk_rate = pclk_rate;
-	msm_host->byte_clk_rate = pclk_bpp;
+	return pclk_bpp;
+}
+
+static void dsi_calc_pclk(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
+{
+	msm_host->pixel_clk_rate = dsi_get_pclk_rate(msm_host->mode, is_bonded_dsi);
+	msm_host->byte_clk_rate = dsi_byte_clk_get_rate(&msm_host->base, is_bonded_dsi,
+							msm_host->mode);
 
 	DBG("pclk=%lu, bclk=%lu", msm_host->pixel_clk_rate,
 				msm_host->byte_clk_rate);
@@ -636,7 +643,7 @@ int dsi_calc_clk_rate_v2(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
 
 	dsi_calc_pclk(msm_host, is_bonded_dsi);
 
-	pclk_bpp = (u64)dsi_get_pclk_rate(msm_host, is_bonded_dsi) * bpp;
+	pclk_bpp = (u64)dsi_get_pclk_rate(msm_host->mode, is_bonded_dsi) * bpp;
 	do_div(pclk_bpp, 8);
 	msm_host->src_clk_rate = pclk_bpp;