linux-kernel - Re: [PATCH v2 2/3] mtd: spi-nor: Altera ASMI Parallel II IP Core

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Date:   Wed, 11 Oct 2017 10:00:37 -0700 (PDT)
From:   matthew.gerlach@...ux.intel.com
To:     Marek Vasut <marek.vasut@...il.com>
cc:     vndao@...era.com, dwmw2@...radead.org, computersforpeace@...il.com,
        boris.brezillon@...e-electrons.com, richard@....at,
        cyrille.pitchen@...ev4u.fr, robh+dt@...nel.org,
        mark.rutland@....com, linux-mtd@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, davem@...emloft.net,
        mchehab@...nel.org, linux-fpga@...r.kernel.org,
        tien.hock.loh@...el.com, hean.loong.ong@...el.com
Subject: Re: [PATCH v2 2/3] mtd: spi-nor: Altera ASMI Parallel II IP Core



On Tue, 10 Oct 2017, Marek Vasut wrote:

> On 09/20/2017 08:28 PM, matthew.gerlach@...ux.intel.com wrote:
>> From: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
>>
>> This patch adds support for a spi-nor, platform driver for the
>> Altera ASMI Parallel II IP Core.  The intended use case is to be able
>> to update the flash used to load a FPGA at power up with mtd-utils.
>>
>> Signed-off-by: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
>> ---
>> v2:
>>     minor checkpatch fixing by Wu Hao <hao.wu@...el.com>
>>     Use read_dummy value as suggested by Cyrille Pitchen.
>>     Don't assume 4 byte addressing (Cryille Pichecn and Marek Vasut).
>>     Fixed #define indenting as suggested by Marek Vasut.
>>     Added units to timer values as suggested by Marek Vasut.
>>     Use io(read|write)8_rep() as suggested by Marek Vasut.
>>     Renamed function prefixed with __ as suggested by Marek Vasut.
>
> [...]
>
>> +#define QSPI_ACTION_REG			0
>> +#define QSPI_ACTION_RST			BIT(0)
>> +#define QSPI_ACTION_EN			BIT(1)
>> +#define QSPI_ACTION_SC			BIT(2)
>> +#define QSPI_ACTION_CHIP_SEL_SFT	4
>> +#define QSPI_ACTION_DUMMY_SFT		8
>> +#define QSPI_ACTION_READ_BACK_SFT	16
>> +
>> +#define QSPI_FIFO_CNT_REG		4
>> +#define QSPI_FIFO_DEPTH			0x200
>> +#define QSPI_FIFO_CNT_MSK		0x3ff
>> +#define QSPI_FIFO_CNT_RX_SFT		0
>> +#define QSPI_FIFO_CNT_TX_SFT		12
>> +
>> +#define QSPI_DATA_REG			0x8
>> +
>> +#define QSPI_POLL_TIMEOUT_US		10000000
>
> 10 s poll timeout ? :)

Hi Marek,

The 10s timeout is fairly arbitrary.  In other words, I pulled it out of 
thin air.  Can you suggest a better timeout?  From a practical standpoint 10s 
seemed to be much better than no timeout when I was debugging bad FPGA 
images.  Without a timeout I was hanging the system when the FPGA image 
failed.  With this timeout, we get a nice message and Linux keeps running 
happily.

Thanks for the feedback,

Matthew Gerlach

>
>> +#define QSPI_POLL_INTERVAL_US		 5 >> + >> +struct 
altera_asmip2 { >
> [...]
>
> Otherwise looks good
>
> -- 
> Best regards,
> Marek Vasut
>