Re: [PATCH v3 3/3] New I2C: Add support for TPM devices over I2C bus

[Stefan Berger]

On 3/24/23 04:24, Cédric Le Goater wrote:
> Hello Ninad,

> > +
> > +/*
> > + * Convert little endian byte stream into local formated
> > + * unsigned integer
> > + */
> > +static inline uint32_t tpm_i2c_le_bytes_to_uint(TPMStateI2C *i2cst)
> > +{
> > +    uint32_t data = 0;
> > +    int      i;
> > +
> > +    assert(i2cst->offset <= 5);  /* Including 0th register value */
> > +
> > +    if (tpm_i2c_is_little_endian()) {
> > +        for (i = 1; i < i2cst->offset; i++) {
> > +            data |= (((uint32_t)i2cst->data[i]) << (8 * (i - 1)));
> > +        }
> > +    } else {
> > +        for (i = 1; i < i2cst->offset; i++) {
> > +            data <<= 8;
> > +            data |= i2cst->data[i];
> > +        }
> > +    }
> > +
> > +    return data;
> > +}
>
> Why is this endianess test  needed ? Something looks wrong.
>
> Could you please explain the endianess used by the various devices and
> the endianness of the MMIO ops ?
>
> If you want to test on a BE host, simply install a debian PPC64 VM/LPAR
> on a POWER9/10 box. I suppose you have access to one in IBM.

I found it's not that simple anymore since all distros moved to little endian. 
I have been using Fedora 28 for big endian tests for swtpm but I have never 
tried it with QEMU...

   Stefan