Message-ID: <259637a6-e63f-56f0-6cdf-6bd21f8e4453@ti.com>
Date:   Wed, 2 Mar 2022 21:00:55 +0530
From:   Apurva Nandan <a-nandan@...com>
To:     Boris Brezillon <boris.brezillon@...labora.com>
CC:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Mark Brown <broonie@...nel.org>,
        Patrice Chotard <patrice.chotard@...s.st.com>,
        Christophe Kerello <christophe.kerello@...s.st.com>,
        Daniel Palmer <daniel@...f.com>,
        Alexander Lobakin <alobakin@...me>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <linux-spi@...r.kernel.org>, <p.yadav@...com>
Subject: Re: [PATCH v3 05/17] mtd: spinand: Define ctrl_ops for non-page
 read/write op templates

Hi Boris,

On 15/02/22 23:07, Boris Brezillon wrote:
> Hi Apurva,
>
> On Tue, 15 Feb 2022 21:03:52 +0530
> Apurva Nandan<a-nandan@...com>  wrote:
>
>> Hi Boris,
>>
>> On 03/01/22 15:31, Boris Brezillon wrote:
>>> On Sat, 1 Jan 2022 13:12:38 +0530
>>> Apurva Nandan<a-nandan@...com>  wrote:
>>>   
>>>> 'ctrl_ops' are op templates for non-page read/write operations,
>>>> which are: reset, get_feature, set_feature, write_enable, block_erase,
>>>> page_read and program_execute ops. The 'ctrl_ops' struct contains in it
>>>> op templates for each of this op, as well as enum spinand_protocol
>>>> denoting protocol of all these ops.
>>>>
>>>> We require these new op templates because of deviation in standard
>>>> SPINAND ops by manufacturers and also due to changes when there is a
>>>> change in SPI protocol/mode. This prevents the core from live-patching
>>>> and vendor-specific adjustments in ops.
>>>>
>>>> Define 'ctrl_ops', add macros to initialize it and add it in
>>>> spinand_device.
>>>>
>>>> Signed-off-by: Apurva Nandan<a-nandan@...com>
>>>> ---
>>>>    include/linux/mtd/spinand.h | 33 +++++++++++++++++++++++++++++++++
>>>>    1 file changed, 33 insertions(+)
>>>>
>>>> diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h
>>>> index 439d8ce40e1d..e5df6220ec1e 100644
>>>> --- a/include/linux/mtd/spinand.h
>>>> +++ b/include/linux/mtd/spinand.h
>>>> @@ -356,6 +356,35 @@ struct spinand_op_variants {
>>>>    			sizeof(struct spi_mem_op),			\
>>>>    	}
>>>>    
>>>> +struct spinand_ctrl_ops {
>>>> +	const struct {
>>>> +		struct spi_mem_op reset;
>>>> +		struct spi_mem_op get_feature;
>>>> +		struct spi_mem_op set_feature;
>>>> +		struct spi_mem_op write_enable;
>>>> +		struct spi_mem_op block_erase;
>>>> +		struct spi_mem_op page_read;
>>>> +		struct spi_mem_op program_execute;
>>>> +	} ops;
>>>> +	const enum spinand_protocol protocol;
>>> Do you really need that protocol field?
>>>   
>>>> +};
>>>> +
>>>> +#define SPINAND_CTRL_OPS(__protocol, __reset, __get_feature, __set_feature,	\
>>>> +			 __write_enable, __block_erase, __page_read,		\
>>>> +			 __program_execute)					\
>>>> +	{									\
>>>> +		.ops = {							\
>>>> +			.reset = __reset,					\
>>>> +			.get_feature = __get_feature,				\
>>>> +			.set_feature = __set_feature,				\
>>>> +			.write_enable = __write_enable,				\
>>>> +			.block_erase = __block_erase,				\
>>>> +			.page_read = __page_read,				\
>>>> +			.program_execute = __program_execute,			\
>>>> +		},								\
>>>> +		.protocol = __protocol,						\
>>>> +	}
>>>> +
>>>>    /**
>>>>     * spinand_ecc_info - description of the on-die ECC implemented by a SPI NAND
>>>>     *		      chip
>>>> @@ -468,6 +497,8 @@ struct spinand_dirmap {
>>>>     * @data_ops.read_cache: read cache op template
>>>>     * @data_ops.write_cache: write cache op template
>>>>     * @data_ops.update_cache: update cache op template
>>>> + * @ctrl_ops: various SPI mem op templates for handling the flash device, i.e.
>>>> + *	      non page-read/write ops.
>>>>     * @select_target: select a specific target/die. Usually called before sending
>>>>     *		   a command addressing a page or an eraseblock embedded in
>>>>     *		   this die. Only required if your chip exposes several dies
>>>> @@ -498,6 +529,8 @@ struct spinand_device {
>>>>    		const struct spi_mem_op *update_cache;
>>>>    	} data_ops;
>>>>    
>>>> +	const struct spinand_ctrl_ops *ctrl_ops;
>>>> +
>>> Okay, I had something slightly different in mind. First, I'd put all
>>> templates in a struct:
>>>
>>> struct spinand_op_templates {
>>> 	const struct spi_mem_op *read_cache;
>>> 	const struct spi_mem_op *write_cache;
>>> 	const struct spi_mem_op *update_cache;
>>> 	const struct spi_mem_op *reset;
>>> 	const struct spi_mem_op *get_feature;
>>> 	const struct spi_mem_op *set_feature;
>>> 	const struct spi_mem_op *write_enable;
>>> 	const struct spi_mem_op *block_erase;
>>> 	const struct spi_mem_op *page_load;
>>> 	const struct spi_mem_op *program_execute;
>>> };
>>>
>>> Then, at the spinand level, I'd define an array of templates:
>>>
>>> enum spinand_protocol {
>>> 	SPINAND_1S_1S_1S,
>>> 	SPINAND_2S_2S_2S,
>>> 	SPINAND_4S_4S_4S,
>>> 	SPINAND_8S_8S_8S,
>>> 	SPINAND_8D_8D_8D,
>>> 	SPINAND_NUM_PROTOCOLS,
>>> };
>>>
>>> struct spinand_device {
>>> 	...
>>> 	enum spinand_protocol protocol;
>>> 	const struct spinand_op_templates *op_templates[SPINAND_NUM_PROTOCOLS];
> It should probably be
>
> 	struct spinand_op_templates op_templates[SPINAND_NUM_PROTOCOLS];
>
> with the spinand_op_templates struct defined as:
>
> struct spinand_op_templates {
>   	struct spi_mem_op read_cache;
>   	struct spi_mem_op write_cache;
>   	struct spi_mem_op update_cache;
>   	struct spi_mem_op reset;
>   	struct spi_mem_op get_feature;
>   	struct spi_mem_op set_feature;
>   	struct spi_mem_op write_enable;
>   	struct spi_mem_op block_erase;
>   	struct spi_mem_op page_load;
>   	struct spi_mem_op program_execute;
> };
>
> so the NAND framework can populate these ops.
>
> Or maybe even better, define an enum that contains all the ops:
>
> enum spinand_op_id {
> 	SPI_NAND_OP_READ_CACHE,
> 	SPI_NAND_OP_WRITE_CACHE,
> 	SPI_NAND_OP_UPDATE_CACHE,
> 	SPI_NAND_OP_RESET,
> ...
> 	SPI_NAND_NUM_OPS,
> };
>
> struct spinand_device {
> 	...
>   	enum spinand_protocol protocol;
>   	struct spi_mem_op op_templates[SPINAND_NUM_PROTOCOLS][SPI_NAND_NUM_OPS];
> 	...
> };
>
>>> This way, you can easily pick the right set of operations based
>>> on the protocol/mode you're in:
>>>
>>> #define spinand_get_op_template(spinand, opname) \
>>> 	((spinand)->op_templates[(spinand)->protocol]->opname)
>>>
>>> static int spinand_read_reg_op(struct spinand_device *spinand, u8 reg, u8 *val)
>>> {
>>> 	struct spi_mem_op op = *spinand_get_op_template(spinand, get_feature);
>>> 	int ret;
>>>
>>> 	...
>>> }
>> I find a couple of issues with this  method,
>>
>> 1. read_cache, write_cache, update_cache op templates don't fit well
>> with the other non-data ops, as
>> these data ops are used to create a dirmap, and that can be done only
>> once at probe time. Hence, there
>> is a different mechanism of selecting of data ops and non-data ops.
> Not sure I see why this is a problem. You can populate data-ops for all
> modes, and pick the one that provides the best perfs when you create
> the dirmap (which should really be at the end of the probe, if it's not
> already).
>
>> Hence, this division in the op templates
>> struct as data_ops and ctrl_ops is required. Currently, the core only
>> supports using a single protocol for
>> data ops, chosen at the time of probing.
> Again, I don't see why you need to differentiate the control and data
> ops when populating this table. Those are just operations the NAND
> supports, and the data operations is just a subset.
>
>> 2. If we use this single op_templates struct, I can't think of any good
>> way to initialize these in the
>> manufacturers driver (winbond.c), refer to 17th patch in this series.
>> Could you please suggest a macro
>> implementation also for winbond.c with the suggested op_templates struct.
> First replace the op_variants field by something more generic:
>
> struct spinand_info {
> ...
> 	const struct spinand_op_variants **ops_variants;
> ...
> };
>
> #define SPINAND_OP_VARIANTS(_id, ...) \
> 	[SPI_NAND_OP_ ## _id] = { __VA_ARGS__ }
>
> #define SPINAND_OPS_VARIANTS(name, ...)
> 	const struct spinand_op_variants name[]{
> 		__VA_ARGS__,
> 	};
>
> #define SPINAND_INFO_OPS_VARIANTS(defs)
> 	.ops_variants = defs
>
> ...
>
> static SPINAND_OPS_VARIANTS(w35n01jw_ops_variants,
> 		SPINAND_OP_VARIANTS(READ_CACHE,
> 			SPINAND_PAGE_READ_FROM_CACHE_OCTALIO_DTR_OP(0, 24, NULL, 0),
> 			SPINAND_PAGE_READ_FROM_CACHE_OP(true, 0, 1, NULL, 0),
> 			...)),
> 		SPINAND_OP_VARIANTS(WRITE_CACHE,
> 			SPINAND_PROG_LOAD_OCTALIO_DTR(true, 0, NULL, 0),
> 			SPINAND_PROG_LOAD(true, 0, NULL, 0)),
> 		...
> 		SPINAND_OP_VARIANTS(RESET,
> 			SPINAND_RESET_OP_OCTAL_DTR,
> 			SPINAND_RESET_OP,
> 		...
> 		);
> ...

I find a issue with this implementation, please give corrective suggestions:

In type of op variant listing, there is no way to specify the protocol 
of the op in the variants struct itself.
     - This will lead to filtering/sorting/searching of ops for finding 
the protocols in the spinand core
     while in spinand_match_and_init(), which I don't feel is a good way 
for protocol based op categorization.
     - This would also lead to complexities in cases of mixed mode 
operations.
     - In addition, we can't simply choose the first supported protocol 
in each op id, as some ops have
     intendependency of protocol with other ops. This is because 
non-data ops (like reset, block erase..)
     cannot be in different protocols at same time, so it would make 
sense to have some form of protocol
     based arrangement while listing them.

> 	SPINAND_INFO("W35N01JW",
> 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0xdc),
> 		     NAND_MEMORG(1, 4096, 128, 64, 512, 20, 1, 1, 1),
> 		     NAND_ECCREQ(1, 512),
> 		     SPINAND_HAS_OCTAL_DTR_BIT | SPINAND_HAS_CR_FEAT_BIT,
> 		     SPINAND_ECCINFO(&w35n01jw_ooblayout, NULL),
> 		     SPINAND_INFO_OPS_VARIANTS(&w35n01jw_ops_variants)),
>
> You also need to adjust spinand_match_and_init() to account for this
> new layout and put each template op in the right subset based on
> op.cmd.width and op.cmd.dtr.
>
> Regards,
>
> Boris

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