linux-kernel - Re: [PATCH v2 6/6] ARM: davinci: da850: configure system configuration chip(CFGCHIP3) for emac

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Message-ID: <CA+V-a8uE6jymk5Z14ydCmuoCAkcLM-ZJKpwp2-0CRXWQtXvTSA@mail.gmail.com>
Date:	Mon, 4 Feb 2013 10:33:15 +0530
From:	Prabhakar Lad <prabhakar.csengg@...il.com>
To:	Sekhar Nori <nsekhar@...com>
Cc:	linux-arm-kernel@...ts.infradead.org,
	davinci-linux-open-source@...ux.davincidsp.com,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	devicetree-discuss@...ts.ozlabs.org, Heiko Schocher <hs@...x.de>,
	"Lad, Prabhakar" <prabhakar.lad@...com>
Subject: Re: [PATCH v2 6/6] ARM: davinci: da850: configure system
 configuration chip(CFGCHIP3) for emac

Sekhar ,

On Sun, Feb 3, 2013 at 6:15 PM, Sekhar Nori <nsekhar@...com> wrote:
> On 1/28/2013 7:17 PM, Prabhakar Lad wrote:
>> From: Lad, Prabhakar <prabhakar.lad@...com>
>>
>> The system configuration chip CFGCHIP3, controls the emac module.
>> This patch appropriately configures this register for emac and
>> sets DA850_MII_MDIO_CLKEN_PIN GPIO pin appropriately.
>>
>> Signed-off-by: Lad, Prabhakar <prabhakar.lad@...com>
>> Cc: linux-arm-kernel@...ts.infradead.org
>> Cc: linux-kernel@...r.kernel.org
>> Cc: davinci-linux-open-source@...ux.davincidsp.com
>> Cc: netdev@...r.kernel.org
>> Cc: devicetree-discuss@...ts.ozlabs.org
>> Cc: Sekhar Nori <nsekhar@...com>
>> Cc: Heiko Schocher <hs@...x.de>
>> ---
>>  arch/arm/mach-davinci/da8xx-dt.c |   28 ++++++++++++++++++++++++++++
>>  1 files changed, 28 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/arm/mach-davinci/da8xx-dt.c b/arch/arm/mach-davinci/da8xx-dt.c
>> index e533a0a..4a096e3 100644
>> --- a/arch/arm/mach-davinci/da8xx-dt.c
>> +++ b/arch/arm/mach-davinci/da8xx-dt.c
>> @@ -8,6 +8,7 @@
>>   * published by the Free Software Foundation.
>>   */
>>  #include <linux/io.h>
>> +#include <linux/gpio.h>
>>  #include <linux/of_irq.h>
>>  #include <linux/of_platform.h>
>>  #include <linux/irqdomain.h>
>> @@ -39,6 +40,32 @@ static void __init da8xx_init_irq(void)
>>
>>  #ifdef CONFIG_ARCH_DAVINCI_DA850
>>
>> +static void __init da8xx_config_emac(void)
>> +{
>> +#define DA850_MII_MDIO_CLKEN_PIN     GPIO_TO_PIN(2, 6)
>> +#define DA850_EMAC_MODE_SELECT               BIT(8)
>> +     void __iomem *cfg_chip3_base;
>> +     int ret;
>> +     u32 val;
>> +
>> +     cfg_chip3_base = DA8XX_SYSCFG0_VIRT(DA8XX_CFGCHIP3_REG);
>> +
>> +     val = __raw_readl(cfg_chip3_base);
>> +     val &= ~DA850_EMAC_MODE_SELECT;
>> +     /* configure the CFGCHIP3 register for MII */
>> +     __raw_writel(val, cfg_chip3_base);
>
> Use readl/writel instead.
>
Ok.

>> +     pr_info("EMAC: MII PHY configured\n");
>> +
>> +     ret = gpio_request(DA850_MII_MDIO_CLKEN_PIN, "mdio_clk_en");
>> +     if (ret) {
>> +             pr_warn("Cannot open GPIO %d\n",
>> +                                     DA850_MII_MDIO_CLKEN_PIN);
>> +             return;
>> +     }
>> +     /* Enable/Disable MII MDIO clock */
>> +     gpio_direction_output(DA850_MII_MDIO_CLKEN_PIN, 0);
>> +}
>> +
>>  struct of_dev_auxdata da8xx_auxdata[] __initdata = {
>>       OF_DEV_AUXDATA("ti,davinci_mdio", 0x01e24000, "davinci_mdio.0", NULL),
>>       OF_DEV_AUXDATA("ti,davinci-dm6467-emac", 0x01e20000, "davinci_emac.1",
>> @@ -52,6 +79,7 @@ static void __init da850_init_machine(void)
>>                            da8xx_auxdata, NULL);
>>
>>       da8xx_uart_clk_enable();
>> +     da8xx_config_emac();
>
> There are couple of issues with this implementation.
>
> 1) da8xx_config_emac() is specific to DA850 EVM, but masquerades as
>    generic for da8xx. Looks like you need two functions, one for soc
>    specific configuration and one board specific.
Ok.

> 2) da8xx_config_emac() goes through all the time, whether the
>    particular board has emac module or not. Shouldn't
>    da8xx_config_emac() check if emac is actually enabled in the passed
>    dtb and only the do the configuration?

Ok. Can you give some pointers how we can access the dtb in board files.

> 3) The function assumes mii is used always, you can use the rmii_en dt
>    property to check if rmii/mii is enabled and configure the soc/board
>    accordingly.

Ok.

> 4) If the same function can work both for da850 and da830, then it can
>    be implemented outside of CONFIG_ARCH_DAVINCI_DA850.
>
Ok.

Regards,
--Prabhakar

> Thanks,
> Sekhar
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