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SubjectRe: [PATCH v9 2/3] spi: Add Renesas R-Car Gen3 RPC-IF SPI controller driver
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Hello!

On 04/03/2019 12:20 PM, masonccyang@mxic.com.tw wrote:

>> >> > +static void rpc_spi_mem_set_prep_op_cfg(struct spi_device *spi,
>> >> > + const struct spi_mem_op *op,
>> >> > + u64 *offs, size_t *len)
>> >> > +{
>> >> > + struct rpc_spi *rpc = spi_controller_get_devdata(spi->controller);
>> >> > +
>> >> > + rpc->cmd = RPC_SMCMR_CMD(op->cmd.opcode);
>> >> > + rpc->smenr = RPC_SMENR_CDE |
>> >> > + RPC_SMENR_CDB(ilog2(op->cmd.buswidth));
>> >> > + rpc->totalxferlen = 1;
>> >> > + rpc->xfer_dir = SPI_MEM_NO_DATA;
>> >> > + rpc->xferlen = 0;
>> >> > + rpc->addr = 0;
>> >> > +
>> >> > + if (op->addr.nbytes) {
>> >> > + rpc->smenr |= RPC_SMENR_ADB(ilog2(op->addr.buswidth));
>> >> > + if (op->addr.nbytes == 4)
>> >> > + rpc->smenr |= RPC_SMENR_ADE(0xf);
>> >> > + else
>> >> > + rpc->smenr |= RPC_SMENR_ADE(0x7);
>> >> > +
>> >> > + if (offs && len)
>> >> > + rpc->addr = *offs;
>> >> > + else
>> >> > + rpc->addr = op->addr.val;
>> >> > + rpc->totalxferlen += op->addr.nbytes;
>> >> > + }
>> >> > +
>> >> > + if (op->dummy.nbytes) {
>> >> > + rpc->smenr |= RPC_SMENR_DME;
>> >> > + rpc->dummy = RPC_SMDMCR_DMCYC(op->dummy.nbytes);
>> >>
>> >> So you haven't fixed this bug? I repeat, the driver doesn't work right
>> >> w/o this fixed!
>> >
>> > Do you mean
>> >
>> > rpc->dummy = RPC_SMDMCR_DMCYC(op->dummy.nbytes) * 8; ?
>>
>> Yes. Or some other code that amounts to it.

Oops, I wasn't attentive enough, I was proposing:

rpc->dummy = RPC_SMDMCR_DMCYC(op->dummy.nbytes * 8);

> why not setting "op->dummy.nbytes = 7" from spi-nor.c protocol layer ?

We want 8 dummy clocks, not 8 dummy bytes. And if you'd looked into
spi_nor_read_sfdp(), you'd have seen that it requests 8 dummy clocks already.

> driver may check device ID or something else to setup op->dummy.nbytes.

The RDSFDP command is not chip specific.

> I think it is not a good idea to *8 in spi host driver.

>> > What is your flash part number?
>>
>> Spansion/Cypress S25FS512S. The datasheet says there must be 8 dummy cycles
>> for the RSFDP command...
>>
>> > The problem you found is in 1 bit or 4 bits width ?
>>
>> 1-bit, I think.
>>
>> >>
>> >> [...]
>> >> > +static ssize_t rpc_spi_mem_dirmap_read(struct spi_mem_dirmap_desc *desc,
>> >> > + u64 offs, size_t len, void *buf)
>> >> > +{
>> >> > + struct rpc_spi *rpc =
>> >> > + spi_controller_get_devdata(desc->mem->spi->controller);
>> >> > + int ret;
>> >> > +
>> >> > + if (offs + desc->info.offset + len > U32_MAX)
>> >> > + return -EINVAL;
>> >> > +
>> >> > + if (len > 0x4000000)
>> >> > + len = 0x4000000;
>> >>
>> >> Ugh...
>> >
>> > by mtd->size ?
>>
>> That'd be better, yes.
>>
>
> Oops, it seems hard to get mtd->size info. from spi_mem_dirmap,

It's in desc->info.length, no?

> I would like to keep 0x4000000.

I'm seeing Boris in the CC's... Boris, is it legitimate to limit
a single dirmap read by the memory "window" size? Or should we try to
serve any valid transfer length?

>> >> > +
>> >> > + ret = rpc_spi_set_freq(rpc, desc->mem->spi->max_speed_hz);
>> >> > + if (ret)
>> >> > + return ret;
>> >> > +
>> >> > + rpc_spi_mem_set_prep_op_cfg(desc->mem->spi,
>> >> > + &desc->info.op_tmpl, &offs, &len);
>> >> > +
>> >> > + regmap_update_bits(rpc->regmap, RPC_CMNCR, RPC_CMNCR_MD, 0);
>> >> > + regmap_write(rpc->regmap, RPC_DRCR, RPC_DRCR_RBURST(32) |
>> >> > + RPC_DRCR_RBE);
>> >> > +
>> >> > + regmap_write(rpc->regmap, RPC_DRCMR, rpc->cmd);
>> >> > + regmap_write(rpc->regmap, RPC_DREAR, RPC_DREAR_EAC(1));
>> >>
>> >> So you're not even trying to support flashes larger than the
>> read dirmap?
>> >> Now I don't think it's acceptable (and I have rewritten this code
>> internally).
>> >
>> > what about the size comes form mtd->size ?
>>
>> I'm not talking about size here; we should use the full address.
>> I'm attaching
>> my patch...
>
> okay,got it!
> what about just
> - regmap_write(rpc->mfd->regmap, RPC_DREAR, RPC_DREAR_EAC(1));
> + regmap_write(rpc->mfd->regmap, RPC_DREAR,
> + RPC_DREAR_EAV(offs >> 25) | RPC_DREAR_EAC(1));
>
> because only > 64MByte size make RPC_DREAR_EAV() work.

Boris, what's your opinion on this?
Note that for the write dirmap we have just 256-byte buffer (reusing
the read cache). Is it legitimate to limit the served length to 256 bytes?

> thanks & best regards,
> Mason

MBR, Sergei

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