linux-kernel - Re: [PATCH RFC 2/2] memory: add Renesas RPC-IF driver

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Date:   Tue, 25 Feb 2020 10:33:10 +0100
From:   "Behme Dirk (CM/ESO2)" <dirk.behme@...bosch.com>
To:     Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
CC:     <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Mason Yang <masonccyang@...c.com.tw>,
        <linux-spi@...r.kernel.org>,
        Chris Brandt <chris.brandt@...esas.com>,
        <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH RFC 2/2] memory: add Renesas RPC-IF driver

On 24.02.2020 19:59, Sergei Shtylyov wrote:
>>>>   From d72b805cc461ab1e9747c973e9be84e7abb8f828 Mon Sep 17 00:00:00 2001
>>>> From: Dirk Behme <dirk.behme@...bosch.com>
>>>> Date: Tue, 4 Feb 2020 08:39:31 +0100
>>>> Subject: [PATCH] memory: renesas-rpc-if: Correct the STRTIM and some other
>>>>    clean up
>>>>
>>>> This is required to make the driver work correctly in my M3 environment.
>>>>
>>>> Signed-off-by: Dirk Behme <dirk.behme@...bosch.com>
>>>> ---
>>>>    drivers/memory/renesas-rpc-if.c | 42 ++++++++++++++++++++-------------
>>>>    1 file changed, 25 insertions(+), 17 deletions(-)
>>>>
>>>> diff --git a/drivers/memory/renesas-rpc-if.c b/drivers/memory/renesas-rpc-if.c
>>>> index 04be92b64bfa..f4356b066384 100644
>>>> --- a/drivers/memory/renesas-rpc-if.c
>>>> +++ b/drivers/memory/renesas-rpc-if.c
>>> [...]
>>>> @@ -513,19 +525,15 @@ ssize_t rpcif_dirmap_read(struct rpcif *rpc, u64 offs, size_t len, void *buf)
>>>>        pm_runtime_get_sync(rpc->dev);
>>>>
>>>>        regmap_update_bits(rpc->regmap, RPCIF_CMNCR, RPCIF_CMNCR_MD, 0);
>>>> -    regmap_write(rpc->regmap, RPCIF_DRCR,
>>>> -             RPCIF_DRCR_RBURST(32) | RPCIF_DRCR_RBE);
>>>> -    regmap_write(rpc->regmap, RPCIF_DRCMR, rpc->command);
>>>> -    regmap_write(rpc->regmap, RPCIF_DREAR,
>>>> -             RPCIF_DREAR_EAV(offs >> 25) | RPCIF_DREAR_EAC(1));
>>>> -    regmap_write(rpc->regmap, RPCIF_DROPR, rpc->option);
>>>> -    regmap_write(rpc->regmap, RPCIF_DRENR,
>>>> -             rpc->enable & ~RPCIF_SMENR_SPIDE(0xF));
>>>> -    regmap_write(rpc->regmap, RPCIF_DRDMCR, rpc->dummy);
>>>> -    regmap_write(rpc->regmap, RPCIF_DRDRENR, rpc->ddr);
>>>
>>>      The driver somehow works only with this left in place (with 2 bytes eaten
>>> as before), otherwise all the flash reads all 0xff (via dirmap).
>>
>>
>> Do you boot from hyperflash?
> 
>     No, I have arewto say 'cpld write 30 1' in U-Boot before a boot a kernel.
> Normally, the V3x Starter Kit boards are wired for the QSPI flash chips.
> 
>> The system I'm using for testing boots from hyperflash. So most probably all registers
>> I don't touch in the driver are put into a reasonable state by the boot code, already.
>> If you don't boot from hyperflash, that at least would explain our different behavior.
> 
>     Yes. Mind dumping the registers and sending to me?


Using the attached debug patch 
(0001-memory-renesas-rpc-if-DEBUG-Dump-register-content.patch) on a 
r8a7796 system booting from Hyperflash with above register dropping 
reverted (i.e. including touching these registers) I get

Before:
RPCIF_DRCR:    0x00000000
RPCIF_DRCMR:   0x00a00000
RPCIF_DREAR:   0x00000000
RPCIF_DROPR:   0x00000000
RPCIF_DRENR:   0xa222d400
RPCIF_DRDMCR:  0x0000000e
RPCIF_DRDRENR: 0x00005101

After:
RPCIF_DRCR:    0x001f0100
RPCIF_DRCMR:   0x00a00000
RPCIF_DREAR:   0x00010001
RPCIF_DROPR:   0x00000000
RPCIF_DRENR:   0xa202d400
RPCIF_DRDMCR:  0x0000000e
RPCIF_DRDRENR: 0x00005101

Comparing that, just 3 registers are different between my working 
version ("Before") and the version which shows the 2-byte offset 
("After"): RPCIF_DRCR, RPCIF_DREAR and RPCIF_DRENR. With try & error, at 
least in my setup, I was able to reduce this to just RPCIF_DRCR. 
Dropping the burst mode I was able to 'fix' the two byte offset issue.

Do you like to give the attached 
0001-memory-renesas-rpc-if-Don-t-use-burst-mode-on-read.patch a try in 
your setup?

Best regards

Dirk


View attachment "0001-memory-renesas-rpc-if-DEBUG-Dump-register-content.patch" of type "text/plain" (2876 bytes)

View attachment "0001-memory-renesas-rpc-if-Don-t-use-burst-mode-on-read.patch" of type "text/plain" (1195 bytes)