Re: [PATCH v2] clk: thead: Fix TH1520 emmc and shdci clock rate

[Drew Fustini <dfustini@tenstorrent.com>]

On Tue, Dec 10, 2024 at 11:30:27AM +0300, bigunclemax@gmail.com wrote:
> From: Maksim Kiselev <bigunclemax@gmail.com>
> 
> In accordance with LicheePi 4A BSP the clock that comes to emmc/sdhci
> is 198Mhz which is got through frequency division of source clock
> VIDEO PLL by 4 [1].
> 
> But now the AP_SUBSYS driver sets the CLK EMMC SDIO to the same
> frequency as the VIDEO PLL, equal to 792 MHz. This causes emmc/sdhci
> to work 4 times slower.
> 
> Let's fix this issue by adding fixed factor clock that divides
> VIDEO PLL by 4 for emmc/sdhci.
> 
> Link: https://github.com/revyos/thead-kernel/blob/7563179071a314f41cdcdbfd8cf6e101e73707f3/drivers/clk/thead/clk-light-fm.c#L454
> 
> Fixes: ae81b69fd2b1 ("clk: thead: Add support for T-Head TH1520 AP_SUBSYS clocks")
> Signed-off-by: Maksim Kiselev <bigunclemax@gmail.com>
> ---
>  drivers/clk/thead/clk-th1520-ap.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/thead/clk-th1520-ap.c b/drivers/clk/thead/clk-th1520-ap.c
> index 17e32ae08720..1015fab95251 100644
> --- a/drivers/clk/thead/clk-th1520-ap.c
> +++ b/drivers/clk/thead/clk-th1520-ap.c
> @@ -779,6 +779,13 @@ static struct ccu_div dpu1_clk = {
>  	},
>  };
>  
> +static CLK_FIXED_FACTOR_HW(emmc_sdio_ref_clk, "emmc-sdio-ref",
> +			   &video_pll_clk.common.hw, 4, 1, 0);
> +
> +static const struct clk_parent_data emmc_sdio_ref_clk_pd[] = {
> +	{ .hw = &emmc_sdio_ref_clk.hw },
> +};
> +
>  static CCU_GATE(CLK_BROM, brom_clk, "brom", ahb2_cpusys_hclk_pd, 0x100, BIT(4), 0);
>  static CCU_GATE(CLK_BMU, bmu_clk, "bmu", axi4_cpusys2_aclk_pd, 0x100, BIT(5), 0);
>  static CCU_GATE(CLK_AON2CPU_A2X, aon2cpu_a2x_clk, "aon2cpu-a2x", axi4_cpusys2_aclk_pd,
> @@ -798,7 +805,7 @@ static CCU_GATE(CLK_PERISYS_APB4_HCLK, perisys_apb4_hclk, "perisys-apb4-hclk", p
>  		0x150, BIT(12), 0);
>  static CCU_GATE(CLK_NPU_AXI, npu_axi_clk, "npu-axi", axi_aclk_pd, 0x1c8, BIT(5), 0);
>  static CCU_GATE(CLK_CPU2VP, cpu2vp_clk, "cpu2vp", axi_aclk_pd, 0x1e0, BIT(13), 0);
> -static CCU_GATE(CLK_EMMC_SDIO, emmc_sdio_clk, "emmc-sdio", video_pll_clk_pd, 0x204, BIT(30), 0);
> +static CCU_GATE(CLK_EMMC_SDIO, emmc_sdio_clk, "emmc-sdio", emmc_sdio_ref_clk_pd, 0x204, BIT(30), 0);
>  static CCU_GATE(CLK_GMAC1, gmac1_clk, "gmac1", gmac_pll_clk_pd, 0x204, BIT(26), 0);
>  static CCU_GATE(CLK_PADCTRL1, padctrl1_clk, "padctrl1", perisys_apb_pclk_pd, 0x204, BIT(24), 0);
>  static CCU_GATE(CLK_DSMART, dsmart_clk, "dsmart", perisys_apb_pclk_pd, 0x204, BIT(23), 0);
> @@ -1059,6 +1066,10 @@ static int th1520_clk_probe(struct platform_device *pdev)
>  		return ret;
>  	priv->hws[CLK_PLL_GMAC_100M] = &gmac_pll_clk_100m.hw;
>  
> +	ret = devm_clk_hw_register(dev, &emmc_sdio_ref_clk.hw);
> +	if (ret)
> +		return ret;
> +
>  	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get, priv);
>  	if (ret)
>  		return ret;
> -- 
> 2.45.2
> 

Reviewed-by: Drew Fustini <dfustini@tenstorrent.com>

Thanks for fixing this. Reads are over 3 times faster now.

6.13-rc1:

  debian@lpi4amain:~$ dd bs=1M count=512 if=/dev/zero of=zero_512M.bin oflag=direct
  512+0 records in
  512+0 records out
  536870912 bytes (537 MB, 512 MiB) copied, 11.8457 s, 45.3 MB/s

  debian@lpi4amain:~$ dd bs=1M if=zero_512M.bin iflag=direct of=/dev/null
  512+0 records in
  512+0 records out
  536870912 bytes (537 MB, 512 MiB) copied, 6.60576 s, 81.3 MB/s

6.13-rc1 with patch:

  debian@lpi4amain:~$ dd bs=1M count=512 if=/dev/zero of=zero_512M.bin oflag=direct
  512+0 records in
  512+0 records out
  536870912 bytes (537 MB, 512 MiB) copied, 11.5359 s, 46.5 MB/s

  debian@lpi4amain:~$ dd bs=1M if=zero_512M.bin iflag=direct of=/dev/null
  512+0 records in
  512+0 records out
  536870912 bytes (537 MB, 512 MiB) copied, 2.03638 s, 264 MB/s

-Drew