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Subject: Re: [PATCHv3] usb: typec: tps6598x: handle block writes separately
 with plain-I2C adapters
From:   Guenter Roeck <linux@roeck-us.net>
To:     Nikolaus Voss <nv@vosn.de>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        Nikolaus Voss <nikolaus.voss@loewensteinmedical.de>
References: <20190220110017.BFA344CE86@mail.steuer-voss.de>
 <20190220151138.12332-1-nv@vosn.de>
 <8dc1a931-c9f7-a46a-42dc-fdcd2274343b@roeck-us.net>
Message-ID: <d4d0f4c7-bcea-2d4e-51d9-97be6f9a48bc@roeck-us.net>
Date:   Wed, 20 Feb 2019 07:36:23 -0800
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On 2/20/19 7:35 AM, Guenter Roeck wrote:
> On 2/20/19 7:11 AM, Nikolaus Voss wrote:
>> From: Nikolaus Voss <nikolaus.voss@loewensteinmedical.de>
>>
>> Commit 1a2f474d328f handles block _reads_ separately with plain-I2C
>> adapters, but the problem described with regmap-i2c not handling
>> SMBus block transfers (i.e. read and writes) correctly also exists
>> with writes.
>>
>> As workaround, this patch adds a block write function the same way
>> 1a2f474d328f adds a block read function.
>>
>> Fixes: 1a2f474d328f ("usb: typec: tps6598x: handle block reads separately with plain-I2C adapters")
>> Fixes: 0a4c005bd171 ("usb: typec: driver for TI TPS6598x USB Power Delivery controllers")
>> Signed-off-by: Nikolaus Voss <nikolaus.voss@loewensteinmedical.de>
> 
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> 
> Note that tps6598x_exec_cmd() is only called with in_len == out_len == 0
> and NULL data pointers. It might make sense to simplify the function and
> drop the unused parameters as well as the associated code.
> 
Clarification: That would be a separate patch.

Guenter

> Guenter
> 
>> ---
>> v2: fix tps6598x_exec_cmd also
>> v3: use fixed length for stack buffer
>> ---
>>   drivers/usb/typec/tps6598x.c | 26 ++++++++++++++++++++------
>>   1 file changed, 20 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/usb/typec/tps6598x.c b/drivers/usb/typec/tps6598x.c
>> index c84c8c189e90..eb8046f87a54 100644
>> --- a/drivers/usb/typec/tps6598x.c
>> +++ b/drivers/usb/typec/tps6598x.c
>> @@ -110,6 +110,20 @@ tps6598x_block_read(struct tps6598x *tps, u8 reg, void *val, size_t len)
>>       return 0;
>>   }
>> +static int tps6598x_block_write(struct tps6598x *tps, u8 reg,
>> +                void *val, size_t len)
>> +{
>> +    u8 data[TPS_MAX_LEN + 1];
>> +
>> +    if (!tps->i2c_protocol)
>> +        return regmap_raw_write(tps->regmap, reg, val, len);
>> +
>> +    data[0] = len;
>> +    memcpy(&data[1], val, len);
>> +
>> +    return regmap_raw_write(tps->regmap, reg, data, sizeof(data));
>> +}
>> +
>>   static inline int tps6598x_read16(struct tps6598x *tps, u8 reg, u16 *val)
>>   {
>>       return tps6598x_block_read(tps, reg, val, sizeof(u16));
>> @@ -127,23 +141,23 @@ static inline int tps6598x_read64(struct tps6598x *tps, u8 reg, u64 *val)
>>   static inline int tps6598x_write16(struct tps6598x *tps, u8 reg, u16 val)
>>   {
>> -    return regmap_raw_write(tps->regmap, reg, &val, sizeof(u16));
>> +    return tps6598x_block_write(tps, reg, &val, sizeof(u16));
>>   }
>>   static inline int tps6598x_write32(struct tps6598x *tps, u8 reg, u32 val)
>>   {
>> -    return regmap_raw_write(tps->regmap, reg, &val, sizeof(u32));
>> +    return tps6598x_block_write(tps, reg, &val, sizeof(u32));
>>   }
>>   static inline int tps6598x_write64(struct tps6598x *tps, u8 reg, u64 val)
>>   {
>> -    return regmap_raw_write(tps->regmap, reg, &val, sizeof(u64));
>> +    return tps6598x_block_write(tps, reg, &val, sizeof(u64));
>>   }
>>   static inline int
>>   tps6598x_write_4cc(struct tps6598x *tps, u8 reg, const char *val)
>>   {
>> -    return regmap_raw_write(tps->regmap, reg, &val, sizeof(u32));
>> +    return tps6598x_block_write(tps, reg, &val, sizeof(u32));
>>   }
>>   static int tps6598x_read_partner_identity(struct tps6598x *tps)
>> @@ -229,8 +243,8 @@ static int tps6598x_exec_cmd(struct tps6598x *tps, const char *cmd,
>>           return -EBUSY;
>>       if (in_len) {
>> -        ret = regmap_raw_write(tps->regmap, TPS_REG_DATA1,
>> -                       in_data, in_len);
>> +        ret = tps6598x_block_write(tps, TPS_REG_DATA1,
>> +                       in_data, in_len);
>>           if (ret)
>>               return ret;
>>       }
>>
>