Re: [PATCH v6 3/3] clk: qcom: Add Global Clock controller (GCC) driver for SDM845

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On 2018-05-02 12:53, Stephen Boyd wrote:
Quoting Amit Nischal (2018-04-30 09:20:10)
---
 .../devicetree/bindings/clock/qcom,gcc.txt         |    1 +
 drivers/clk/qcom/Kconfig                           |   10 +-
 drivers/clk/qcom/Makefile                          |    1 +
drivers/clk/qcom/gcc-sdm845.c | 3480 ++++++++++++++++++++
 include/dt-bindings/clock/qcom,gcc-sdm845.h        |  239 ++

Do the split that Rob suggests please, given that you're resending. And
also include his reviewed-by tag.

Thanks for the review. Sure I will split the dt-binding into
separate patch in next series.


 5 files changed, 3727 insertions(+), 4 deletions(-)
 create mode 100644 drivers/clk/qcom/gcc-sdm845.c
 create mode 100644 include/dt-bindings/clock/qcom,gcc-sdm845.h

diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig
index e42e1af..3298beb 100644
--- a/drivers/clk/qcom/Kconfig
+++ b/drivers/clk/qcom/Kconfig
@@ -218,13 +218,15 @@ config MSM_MMCC_8996
Say Y if you want to support multimedia devices such as display,
          graphics, video encode/decode, camera, etc.

-config MSM_GCC_8998
-       tristate "MSM8998 Global Clock Controller"
+config SDM_GCC_845
+       tristate "SDM845 Global Clock Controller"
+       select QCOM_GDSC
        depends on COMMON_CLK_QCOM
        help
-         Support for the global clock controller on msm8998 devices.
+ Support for the global clock controller on Qualcomm Technologies, Inc
+         sdm845 devices.
Say Y if you want to use peripheral devices such as UART, SPI,
-         i2c, USB, UFS, SD/eMMC, PCIe, etc.
+         I2C, USB, UFS, SDDC, PCIe, etc.

This is all wrong.


My bad. I did by mistake. Will fix this in next series.


 config SPMI_PMIC_CLKDIV
        tristate "SPMI PMIC clkdiv Support"
diff --git a/drivers/clk/qcom/gcc-sdm845.c b/drivers/clk/qcom/gcc-sdm845.c
new file mode 100644
index 0000000..6484cba
--- /dev/null
+++ b/drivers/clk/qcom/gcc-sdm845.c
@@ -0,0 +1,3480 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018, The Linux Foundation. All rights reserved.
+ */
+
[...]
+                       .name = "gcc_disp_axi_clk",
+                       .ops = &clk_branch2_ops,
+               },
+       },
+};
+
+static struct clk_branch gcc_disp_gpll0_clk_src = {
+       .halt_reg = 0x52004,
+       .halt_check = BRANCH_HALT_DELAY,

What about this one? It's not a phy so I'm confused again why we're
unable to check the halt bit. To be clear(er), I don't see why we ever
want to have HALT_DELAY used. Hopefully we can remove that flag.

From what I recall, the flag is there for clks that don't toggle their
status bit at all, but that we know take a few cycles to ungate the
upstream clk. So we threw a delay into the code to make sure that when
clk_enable() returned, a driver wouldn't try to use hardware before the
clk was actually on. But these cases should pretty much never happen,
hence all the pushback against this flag.


For these "*gpll0_clk_src" and "*gpll0_div_clk" clocks, there is no halt
bit to check the status and it is required to have delay for few cycles
so that clock gets turned on before a client driver to use the hardware.

+       .clkr = {
+               .enable_reg = 0x52004,
+               .enable_mask = BIT(18),
+               .hw.init = &(struct clk_init_data){
+                       .name = "gcc_disp_gpll0_clk_src",
+                       .parent_names = (const char *[]){
+                               "gpll0",
+                       },
+                       .num_parents = 1,
[...]
+               .enable_reg = 0x7508c,
+               .enable_mask = BIT(0),
+               .hw.init = &(struct clk_init_data){
+                       .name = "gcc_ufs_card_phy_aux_clk",
+                       .parent_names = (const char *[]){
+                               "gcc_ufs_card_phy_aux_clk_src",
+                       },
+                       .num_parents = 1,
+                       .flags = CLK_SET_RATE_PARENT,
+                       .ops = &clk_branch2_ops,
+               },
+       },
+};
+
+static struct clk_branch gcc_ufs_card_rx_symbol_0_clk = {
+       .halt_reg = 0x75018,
+       .halt_check = BRANCH_HALT_DELAY,

There are still HALT_DELAY flags for UFS though? Why?

For ufs_card tx/rx symbol clocks, we don't poll the status bit as
per the recommendation from the HW team. We can change the halt_check
type to newly implemented flag "BRANCH_HALT_SKIP". Please update us with
your thoughts to change the flag to "BRANCH_HALT_SKIP".


Also, are you going to send DFS support for the QUP clks? I would like
to see that code merged soon.

Taniya has sent the patches for DFS support for QUP clocks.
https://patchwork.kernel.org/patch/10376951/

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