linux-kernel - Re: [PATCH 2/2] clk: aspeed: Setup video engine clocking

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Message-Id: <81b100b7-252e-3145-fb34-17a9c0cdd91e@linux.ibm.com>
Date:   Fri, 14 Dec 2018 09:47:53 -0600
From:   Eddie James <eajames@...ux.ibm.com>
To:     Joel Stanley <joel@....id.au>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-aspeed@...ts.ozlabs.org, Andrew Jeffery <andrew@...id.au>,
        Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        linux-clk@...r.kernel.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 2/2] clk: aspeed: Setup video engine clocking



On 12/13/2018 07:02 PM, Joel Stanley wrote:
> Hi Eddie,
>
> On Wed, 12 Dec 2018 at 06:42, Eddie James <eajames@...ux.ibm.com> wrote:
>> Add the video engine reset bit. Add eclk mux and clock divider table.
>>
>> Signed-off-by: Eddie James <eajames@...ux.ibm.com>
>> Acked-by: Stephen Boyd <sboyd@...nel.org>
>> ---
>>   drivers/clk/clk-aspeed.c | 41 +++++++++++++++++++++++++++++++++++++++--
>>   1 file changed, 39 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/clk/clk-aspeed.c b/drivers/clk/clk-aspeed.c
>> index 5961367..f16ce7d 100644
>> --- a/drivers/clk/clk-aspeed.c
>> +++ b/drivers/clk/clk-aspeed.c
>> @@ -87,7 +87,7 @@ struct aspeed_clk_gate {
>>   /* TODO: ask Aspeed about the actual parent data */
>>   static const struct aspeed_gate_data aspeed_gates[] = {
>>          /*                               clk rst   name                 parent  flags */
>> -       [ASPEED_CLK_GATE_ECLK] =        {  0, -1, "eclk-gate",          "eclk", 0 }, /* Video Engine */
>> +       [ASPEED_CLK_GATE_ECLK] =        {  0,  6, "eclk-gate",          "eclk", 0 }, /* Video Engine */
>
>>          [ASPEED_CLK_GATE_GCLK] =        {  1,  7, "gclk-gate",          NULL,   0 }, /* 2D engine */
>>          [ASPEED_CLK_GATE_MCLK] =        {  2, -1, "mclk-gate",          "mpll", CLK_IS_CRITICAL }, /* SDRAM */
>>          [ASPEED_CLK_GATE_VCLK] =        {  3,  6, "vclk-gate",          NULL,   0 }, /* Video Capture */
>> @@ -113,6 +113,24 @@ struct aspeed_clk_gate {
>>          [ASPEED_CLK_GATE_LHCCLK] =      { 28, -1, "lhclk-gate",         "lhclk", 0 }, /* LPC master/LPC+ */
>>   };
>>
>> +static const char * const eclk_parent_names[] = {
>> +       "mpll",
> Is the mpll really an input to the eclk?

Yep, it's the default.

>
>> +       "hpll",
>> +       "dpll",
> We don't have a dpll in the driver that I can see.

True... I supposed I would just add the parent here now in case the dpll 
clock is ever added.

>
>> +};
>> +
>> +static const struct clk_div_table ast2500_eclk_div_table[] = {
> Is the clocking setup different on the ast2400?

Yes, the dividers are the default ast2400 ones.

>
>> +       { 0x0, 2 },
>> +       { 0x1, 2 },
>> +       { 0x2, 3 },
>> +       { 0x3, 4 },
>> +       { 0x4, 5 },
>> +       { 0x5, 6 },
>> +       { 0x6, 7 },
>> +       { 0x7, 8 },
>> +       { 0 }
>> +};
>> @@ -317,6 +338,7 @@ struct aspeed_reset {
>>          [ASPEED_RESET_PECI]     = 10,
>>          [ASPEED_RESET_I2C]      =  2,
>>          [ASPEED_RESET_AHB]      =  1,
>> +       [ASPEED_RESET_VIDEO]    =  6,
> You've added the reset line to the ASPEED_CLK_GATE_ECLK clock so you
> do not need to separately expose the reset controller. Instead
> enabling the clock will deassert the rest line for you.
>
> This means you should drop the change from the header too, and it
> affects the bindings document for the video engine.

I want that reset available separately for use in the video engine 
actually. I could do without it, but it's somewhat useful.

Thanks,
Eddie

>
>>          /*
>>           * SCUD4 resets start at an offset to separate them from
>> @@ -522,6 +544,22 @@ static int aspeed_clk_probe(struct platform_device *pdev)
>>                  return PTR_ERR(hw);
>>          aspeed_clk_data->hws[ASPEED_CLK_24M] = hw;
>>
>> +       hw = clk_hw_register_mux(dev, "eclk-mux", eclk_parent_names,
>> +                                ARRAY_SIZE(eclk_parent_names), 0,
>> +                                scu_base + ASPEED_CLK_SELECTION, 2, 0x3, 0,
>> +                                &aspeed_clk_lock);
>> +       if (IS_ERR(hw))
>> +               return PTR_ERR(hw);
>> +       aspeed_clk_data->hws[ASPEED_CLK_ECLK_MUX] = hw;
>> +
>> +       hw = clk_hw_register_divider_table(dev, "eclk", "eclk-mux", 0,
>> +                                          scu_base + ASPEED_CLK_SELECTION, 28,
>> +                                          3, 0, soc_data->eclk_div_table,
>> +                                          &aspeed_clk_lock);
>> +       if (IS_ERR(hw))
>> +               return PTR_ERR(hw);
>> +       aspeed_clk_data->hws[ASPEED_CLK_ECLK] = hw;
>> +
>>          /*
>>           * TODO: There are a number of clocks that not included in this driver
>>           * as more information is required:
>> @@ -531,7 +569,6 @@ static int aspeed_clk_probe(struct platform_device *pdev)
>>           *   RGMII
>>           *   RMII
>>           *   UART[1..5] clock source mux
>> -        *   Video Engine (ECLK) mux and clock divider
>>           */
>>
>>          for (i = 0; i < ARRAY_SIZE(aspeed_gates); i++) {
>> --
>> 1.8.3.1
>>