linux-kernel - Re: [PATCH 2/2] i2c: xgene-slimpro: Add ACPI support by using PCC mailbox

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Message-ID: <20170420080552.7hymw4gqy4kzecns@ninjato>
Date:   Thu, 20 Apr 2017 10:05:52 +0200
From:   Wolfram Sang <wsa@...-dreams.de>
To:     Hoan Tran <hotran@....com>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Loc Ho <lho@....com>, Keyur Chudgar <kchudgar@....com>
Subject: Re: [PATCH 2/2] i2c: xgene-slimpro: Add ACPI support by using PCC
 mailbox

Hi,

have you tested these patches also without PCC? So, we can be sure there
is no regression?

> diff --git a/drivers/i2c/busses/i2c-xgene-slimpro.c b/drivers/i2c/busses/i2c-xgene-slimpro.c
> index 96545aa..a5771c1 100644
> --- a/drivers/i2c/busses/i2c-xgene-slimpro.c
> +++ b/drivers/i2c/busses/i2c-xgene-slimpro.c
> @@ -32,6 +32,8 @@
>  #include <linux/platform_device.h>
>  #include <linux/version.h>
>  
> +#include <acpi/pcc.h>
> +

Please keep it sorted alphabetically.

> +#define PCC_CMD_GENERATE_DB_INT		BIT(15)
> +#define PCC_STS_CMD_COMPLETE		BIT(0)
> +#define PCC_STS_SCI_DOORBELL		BIT(1)
> +#define PCC_STS_ERR			BIT(2)
> +#define PCC_STS_PLAT_NOTIFY		BIT(3)

Please keep it sorted by number.

> +	if (!acpi_disabled) {
> +		mutex_lock(&ctx->tx_mutex);
> +		init_completion(&ctx->rd_complete);

reinit_completion?

> +		slimpro_i2c_pcc_tx_prepare(ctx, msg);
> +	}
> +
> +	mutex_init(&ctx->tx_mutex);

Why this mutex, by the way? The i2c-core serializes access to the
adapter. Maybe I am missing something?

> +		cppc_ss = ctx->mbox_chan->con_priv;
> +		if (!cppc_ss) {
> +			dev_err(&pdev->dev, "PPC subspace not found\n");
> +			rc = -ENODEV;
> +			goto mbox_err;
> +		}
> +
> +		if (!ctx->mbox_chan->mbox->txdone_irq) {
> +			dev_err(&pdev->dev, "PCC IRQ not supported\n");
> +			rc = -ENODEV;
> +			goto mbox_err;
> +		}
>  
> +		/*
> +		 * This is the shared communication region
> +		 * for the OS and Platform to communicate over.
> +		 */
> +		ctx->comm_base_addr = cppc_ss->base_address;
> +		if (ctx->comm_base_addr) {
> +			ctx->pcc_comm_addr = memremap(ctx->comm_base_addr,
> +						      cppc_ss->length,
> +						      MEMREMAP_WB);
> +		} else {
> +			dev_err(&pdev->dev, "Failed to get PCC comm region\n");
> +			rc = -ENODEV;
> +			goto mbox_err;
> +		}

I think it doesn't make sense to print a dev_err and return ENODEV which
is treated by the driver core as a non-error. It means "not present, but
OK". You probably want other error codes here.

Regards,

   Wolfram


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