On 10.06.2022 13:03, Jean Delvare wrote:
> Hi Heiner,
>
> On Fri, 15 Apr 2022 18:58:03 +0200, Heiner Kallweit wrote:
>> This patch factors out non-block pre/post processing to a new function
>> i801_single_transaction(), complementing existing function
>> i801_block_transaction(). This makes i801_access() better readable.
>
> I like the idea, but I have objections about some implementation
> details, see below.
>
>> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
>> ---
>> drivers/i2c/busses/i2c-i801.c | 95 +++++++++++++++++++++--------------
>> 1 file changed, 58 insertions(+), 37 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
>> index bf77f8640..8c2245f38 100644
>> --- a/drivers/i2c/busses/i2c-i801.c
>> +++ b/drivers/i2c/busses/i2c-i801.c
>> @@ -771,6 +771,62 @@ static int i801_block_transaction(struct i801_priv *priv, union i2c_smbus_data *
>> return result;
>> }
>>
>> +/* Single transaction function */
>
> The term "single transaction" is a bit misleading. Block transactions
> are also single transactions, in the sense that there's one start
> condition at the beginning and one stop condition at the end. I'd
> rather call non-block transactions "single value transactions" or
> "simple transactions".
>
OK
>> +static int i801_single_transaction(struct i801_priv *priv, union i2c_smbus_data *data,
>> + char read_write, int command)
>> +{
>> + int xact, ret;
>> +
>> + switch (command) {
>> + case I2C_SMBUS_QUICK:
>> + xact = I801_QUICK;
>> + break;
>> + case I2C_SMBUS_BYTE:
>> + xact = I801_BYTE;
>> + break;
>
> Previous 2 lines are indented with spaces instead of tabs.
>
OK
>> + case I2C_SMBUS_BYTE_DATA:
>> + if (read_write == I2C_SMBUS_WRITE)
>> + outb_p(data->byte, SMBHSTDAT0(priv));
>> + xact = I801_BYTE_DATA;
>> + break;
>> + case I2C_SMBUS_WORD_DATA:
>> + if (read_write == I2C_SMBUS_WRITE) {
>> + outb_p(data->word & 0xff, SMBHSTDAT0(priv));
>> + outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv));
>> + }
>> + xact = I801_WORD_DATA;
>> + break;
>> + case I2C_SMBUS_PROC_CALL:
>> + outb_p(data->word & 0xff, SMBHSTDAT0(priv));
>> + outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv));
>> + xact = I801_PROC_CALL;
>> + break;
>> + default:
>> + return -EOPNOTSUPP;
>
> That's never going to happen.
>
> Generally speaking, I'm worried about having the same switch/case
> construct here that we already have in i801_access. Looks to me like we
> are doing half of the work here and the other half there and I fail to
> see the rationale for splitting the work like that. I mean, I see how
> it solves the asymmetry between the block and non-block code paths, but
> the result doesn't look appealing. From a performance perspective it's
> questionable too.
>
> What prevents us from doing all the work on either side? Maybe we
> should move more code into i801_single_transaction (possibly in a
> subsequent patch)?
>
Makes sense. Ill add this in v2.
>> + }
>> +
>> + ret = i801_transaction(priv, xact);
>> +
>
> Traditionally no blank line here.
>
OK
>> + if (ret || read_write == I2C_SMBUS_WRITE)
>> + return ret;
>> +
>> + switch (command) {
>> + case I2C_SMBUS_BYTE:
>> + case I2C_SMBUS_BYTE_DATA:
>> + data->byte = inb_p(SMBHSTDAT0(priv));
>> + break;
>> + case I2C_SMBUS_WORD_DATA:
>> + case I2C_SMBUS_PROC_CALL:
>> + data->word = inb_p(SMBHSTDAT0(priv)) +
>> + (inb_p(SMBHSTDAT1(priv)) << 8);
>> + break;
>> + default:
>> + break;
>
> Default case is not needed.
>
OK
>> + }
>> +
>> + return 0;
>> +}
>> +
>> static void i801_set_hstadd(struct i801_priv *priv, u8 addr, char read_write)
>> {
>> addr <<= 1;
>> @@ -784,9 +840,7 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr,
>> unsigned short flags, char read_write, u8 command,
>> int size, union i2c_smbus_data *data)
>> {
>> - int hwpec;
>> - int block = 0;
>> - int ret, xact;
>> + int hwpec, ret, block = 0;
>> struct i801_priv *priv = i2c_get_adapdata(adap);
>>
>> mutex_lock(&priv->acpi_lock);
>> @@ -804,36 +858,23 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr,
>> switch (size) {
>> case I2C_SMBUS_QUICK:
>> i801_set_hstadd(priv, addr, read_write);
>> - xact = I801_QUICK;
>> break;
>> case I2C_SMBUS_BYTE:
>> i801_set_hstadd(priv, addr, read_write);
>> if (read_write == I2C_SMBUS_WRITE)
>> outb_p(command, SMBHSTCMD(priv));
>> - xact = I801_BYTE;
>> break;
>> case I2C_SMBUS_BYTE_DATA:
>> i801_set_hstadd(priv, addr, read_write);
>> outb_p(command, SMBHSTCMD(priv));
>> - if (read_write == I2C_SMBUS_WRITE)
>> - outb_p(data->byte, SMBHSTDAT0(priv));
>> - xact = I801_BYTE_DATA;
>> break;
>> case I2C_SMBUS_WORD_DATA:
>> i801_set_hstadd(priv, addr, read_write);
>> outb_p(command, SMBHSTCMD(priv));
>> - if (read_write == I2C_SMBUS_WRITE) {
>> - outb_p(data->word & 0xff, SMBHSTDAT0(priv));
>> - outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv));
>> - }
>> - xact = I801_WORD_DATA;
>> break;
>> case I2C_SMBUS_PROC_CALL:
>> i801_set_hstadd(priv, addr, I2C_SMBUS_WRITE);
>> outb_p(command, SMBHSTCMD(priv));
>> - outb_p(data->word & 0xff, SMBHSTDAT0(priv));
>> - outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv));
>> - xact = I801_PROC_CALL;
>> read_write = I2C_SMBUS_READ;
>> break;
>> case I2C_SMBUS_BLOCK_DATA:
>> @@ -883,7 +924,7 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr,
>> if (block)
>> ret = i801_block_transaction(priv, data, read_write, size);
>> else
>> - ret = i801_transaction(priv, xact);
>> + ret = i801_single_transaction(priv, data, read_write, size);
>>
>> /* Some BIOSes don't like it when PEC is enabled at reboot or resume
>> time, so we forcibly disable it after every transaction. Turn off
>> @@ -891,26 +932,6 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr,
>> if (hwpec || block)
>> outb_p(inb_p(SMBAUXCTL(priv)) &
>> ~(SMBAUXCTL_CRC | SMBAUXCTL_E32B), SMBAUXCTL(priv));
>> -
>> - if (block)
>> - goto out;
>> - if (ret)
>> - goto out;
>> - if ((read_write == I2C_SMBUS_WRITE) || (xact == I801_QUICK))
>> - goto out;
>> -
>> - switch (xact) {
>> - case I801_BYTE: /* Result put in SMBHSTDAT0 */
>> - case I801_BYTE_DATA:
>> - data->byte = inb_p(SMBHSTDAT0(priv));
>> - break;
>> - case I801_WORD_DATA:
>> - case I801_PROC_CALL:
>> - data->word = inb_p(SMBHSTDAT0(priv)) +
>> - (inb_p(SMBHSTDAT1(priv)) << 8);
>> - break;
>> - }
>> -
>> out:
>> /*
>> * Unlock the SMBus device for use by BIOS/ACPI,
>
>
