Re: [PATCH v2 2/2] spi: fsl-spi: Implement trailing bits

[kernel test robot <lkp@xxxxxxxxx>]

Hi Christophe,

I love your patch! Yet something to improve:

[auto build test ERROR on v5.17-rc6]
[cannot apply to broonie-spi/for-next next-20220228]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Christophe-Leroy/Add-support-for-components-requiring-trailing-clock-after-transfer/20220228-231740
base:    7e57714cd0ad2d5bb90e50b5096a0e671dec1ef3
config: alpha-allyesconfig (https://download.01.org/0day-ci/archive/20220301/202203010212.oQMKRiPl-lkp@xxxxxxxxx/config)
compiler: alpha-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/7eb07c4d26401389204fcc6cf685c18c89b64ef8
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Christophe-Leroy/Add-support-for-components-requiring-trailing-clock-after-transfer/20220228-231740
        git checkout 7eb07c4d26401389204fcc6cf685c18c89b64ef8
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=alpha SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All errors (new ones prefixed by >>):

   drivers/spi/spi-fsl-spi.c: In function 'fsl_spi_do_one_msg':
>> drivers/spi/spi-fsl-spi.c:435:35: error: 'empty_zero_page' undeclared (first use in this function)
     435 |                         .tx_buf = empty_zero_page,
         |                                   ^~~~~~~~~~~~~~~
   drivers/spi/spi-fsl-spi.c:435:35: note: each undeclared identifier is reported only once for each function it appears in


vim +/empty_zero_page +435 drivers/spi/spi-fsl-spi.c

   356	
   357	static int fsl_spi_do_one_msg(struct spi_master *master,
   358				      struct spi_message *m)
   359	{
   360		struct mpc8xxx_spi *mpc8xxx_spi = spi_master_get_devdata(master);
   361		struct spi_device *spi = m->spi;
   362		struct spi_transfer *t, *first;
   363		unsigned int cs_change;
   364		const int nsecs = 50;
   365		int status, last_bpw;
   366	
   367		/*
   368		 * In CPU mode, optimize large byte transfers to use larger
   369		 * bits_per_word values to reduce number of interrupts taken.
   370		 */
   371		if (!(mpc8xxx_spi->flags & SPI_CPM_MODE)) {
   372			list_for_each_entry(t, &m->transfers, transfer_list) {
   373				if (t->len < 256 || t->bits_per_word != 8)
   374					continue;
   375				if ((t->len & 3) == 0)
   376					t->bits_per_word = 32;
   377				else if ((t->len & 1) == 0)
   378					t->bits_per_word = 16;
   379			}
   380		}
   381	
   382		/* Don't allow changes if CS is active */
   383		cs_change = 1;
   384		list_for_each_entry(t, &m->transfers, transfer_list) {
   385			if (cs_change)
   386				first = t;
   387			cs_change = t->cs_change;
   388			if (first->speed_hz != t->speed_hz) {
   389				dev_err(&spi->dev,
   390					"speed_hz cannot change while CS is active\n");
   391				return -EINVAL;
   392			}
   393		}
   394	
   395		last_bpw = -1;
   396		cs_change = 1;
   397		status = -EINVAL;
   398		list_for_each_entry(t, &m->transfers, transfer_list) {
   399			if (cs_change || last_bpw != t->bits_per_word)
   400				status = fsl_spi_setup_transfer(spi, t);
   401			if (status < 0)
   402				break;
   403			last_bpw = t->bits_per_word;
   404	
   405			if (cs_change) {
   406				fsl_spi_chipselect(spi, BITBANG_CS_ACTIVE);
   407				ndelay(nsecs);
   408			}
   409			cs_change = t->cs_change;
   410			if (t->len)
   411				status = fsl_spi_bufs(spi, t, m->is_dma_mapped);
   412			if (status) {
   413				status = -EMSGSIZE;
   414				break;
   415			}
   416			m->actual_length += t->len;
   417	
   418			spi_transfer_delay_exec(t);
   419	
   420			if (cs_change) {
   421				ndelay(nsecs);
   422				fsl_spi_chipselect(spi, BITBANG_CS_INACTIVE);
   423				ndelay(nsecs);
   424			}
   425		}
   426	
   427		if (status || !cs_change) {
   428			ndelay(nsecs);
   429			fsl_spi_chipselect(spi, BITBANG_CS_INACTIVE);
   430		}
   431	
   432		if (!status && spi->trailing_bits) {
   433			struct spi_transfer t = {
   434				.len = 1,
 > 435				.tx_buf = empty_zero_page,
   436			};
   437	
   438			if (spi->trailing_bits < 4)
   439				t.bits_per_word = 4;
   440			else if (spi->trailing_bits > 8)
   441				t.bits_per_word = 16;
   442			else
   443				t.bits_per_word = spi->trailing_bits;
   444	
   445			status = fsl_spi_setup_transfer(spi, &t);
   446			if (!status)
   447				status = fsl_spi_bufs(spi, &t, 0);
   448		}
   449		m->status = status;
   450	
   451		fsl_spi_setup_transfer(spi, NULL);
   452		spi_finalize_current_message(master);
   453		return 0;
   454	}
   455	

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