Re: [PATCHv2 6/6] mmc: dw_mmc: Add support DW SD/MMC driver on SOCFPGA

[Dinh Nguyen <dinh.linux@gmail.com>]

Hi Pavel,

On 05/17/2013 06:46 AM, Pavel Machek wrote:
> Hi!
> 
>> Add platform specific functionality for the DW SD/MMC driver for
>> SoCFPGA. Move SDMMC_CMD_USE_HOLD_REG to dw_mmc.h so other platforms
>> can use this define.
> 
>> --- /dev/null
>> +++ b/drivers/mmc/host/dw_mmc-socfpga.c
>> @@ -0,0 +1,139 @@
>> +/*
>> + * Altera SoCFPGA Specific Extensions for Synopsys DW Multimedia Card Interface driver
>> + *
>> + *  Copyright (C) 2012, Samsung Electronics Co., Ltd.
>> + *  Copyright (C) 2013 Altera Corporation
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * Taken from dw_mmc_exynos.c
> 
> Actually it is   dw_mmc-exynos.c

Will fix in rev3.

> 
>> +#define SYSMGR_SDMMCGRP_CTRL_OFFSET		0x108
>> +#define DRV_CLK_PHASE_SHIFT_SEL_MASK	0x7
>> +#define SYSMGR_SDMMC_CTRL_SET(smplsel, drvsel)		\
>> +	((((drvsel) << 0) & 0x7) | (((smplsel) << 3) & 0x38))
> 
> Should SYSMGR stuff go to shared header file somewhere?
> 
>> +extern void __iomem *sys_manager_base_addr;
> 
> This is unused.

Will remove.

> 
>> +/* SOCFPGA implementation specific driver private data */
>> +struct dw_mci_socfpga_priv_data {
>> +	u8	ciu_div;
> 
> comment would be nice, something like
> /* card interface unit divisor */ ?
> 
>> +	u32	hs_timing;
> 
> /* card interface unit phase shift for RX/TX mode */
> ?

Will add comments.

> 
>> +static int dw_mci_socfpga_setup_clock(struct dw_mci *host)
>> +{
>> +	struct dw_mci_socfpga_priv_data *priv = host->priv;
>> +
>> +	clk_disable(host->ciu_clk);
>> +	regmap_write(priv->sysreg, SYSMGR_SDMMCGRP_CTRL_OFFSET, priv->hs_timing);
>> +	clk_enable(host->ciu_clk);
>> +
>> +	host->bus_hz /= (priv->ciu_div + 1);
> 
> Previous version said:
> 
> +       host->bus_hz /= priv->ciu_div;
> 
> I see you want to avoid division by zero, but this will introduce
> significant error for low divisors, right? Is divisor of 0 valid?

Divisor of 0 is not valid. Not sure what you mean my low divisos?

Thanks,
Dinh
> 
> Otherwise it looks good. Thanks,
> 									Pavel
>