* Re: [PATCH] staging: fbtft: fix unaligned vmem writes when txbuf is byte-offset
2026-06-25 11:02 ` [PATCH] staging: fbtft: fix unaligned vmem writes when txbuf is byte-offset suryasaimadhu
@ 2026-06-25 13:20 ` kernel test robot
2026-06-25 13:53 ` kernel test robot
2026-06-25 13:59 ` Andy Shevchenko
2 siblings, 0 replies; 4+ messages in thread
From: kernel test robot @ 2026-06-25 13:20 UTC (permalink / raw)
To: suryasaimadhu, andy
Cc: oe-kbuild-all, gregkh, dri-devel, linux-fbdev, linux-staging,
linux-kernel, suryasaimadhu
Hi suryasaimadhu,
kernel test robot noticed the following build errors:
[auto build test ERROR on staging/staging-testing]
url: https://github.com/intel-lab-lkp/linux/commits/suryasaimadhu/staging-fbtft-fix-unaligned-vmem-writes-when-txbuf-is-byte-offset/20260625-190423
base: staging/staging-testing
patch link: https://lore.kernel.org/r/20260625110237.304435-1-suryasaimadhu369%40gmail.com
patch subject: [PATCH] staging: fbtft: fix unaligned vmem writes when txbuf is byte-offset
config: sh-allmodconfig (https://download.01.org/0day-ci/archive/20260625/202606252119.rClVa8On-lkp@intel.com/config)
compiler: sh4-linux-gcc (GCC) 16.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260625/202606252119.rClVa8On-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202606252119.rClVa8On-lkp@intel.com/
All errors (new ones prefixed by >>):
drivers/staging/fbtft/fbtft-bus.c: In function 'fbtft_write_vmem16_bus8':
>> drivers/staging/fbtft/fbtft-bus.c:157:25: error: implicit declaration of function 'put_unaligned' [-Wimplicit-function-declaration]
157 | put_unaligned(cpu_to_be16(vmem16[i]), &txbuf16[i]);
| ^~~~~~~~~~~~~
vim +/put_unaligned +157 drivers/staging/fbtft/fbtft-bus.c
113
114 /*****************************************************************************
115 *
116 * int (*write_vmem)(struct fbtft_par *par);
117 *
118 *****************************************************************************/
119
120 /* 16 bit pixel over 8-bit databus */
121 int fbtft_write_vmem16_bus8(struct fbtft_par *par, size_t offset, size_t len)
122 {
123 u16 *vmem16;
124 __be16 *txbuf16 = par->txbuf.buf;
125 size_t remain;
126 size_t to_copy;
127 size_t tx_array_size;
128 int i;
129 int ret = 0;
130 size_t startbyte_size = 0;
131
132 remain = len / 2;
133 vmem16 = (u16 *)(par->info->screen_buffer + offset);
134
135 gpiod_set_value(par->gpio.dc, 1);
136
137 /* non buffered write */
138 if (!par->txbuf.buf)
139 return par->fbtftops.write(par, vmem16, len);
140
141 /* buffered write */
142 tx_array_size = par->txbuf.len / 2;
143
144 if (par->startbyte) {
145 txbuf16 = par->txbuf.buf + 1;
146 tx_array_size -= 2;
147 *(u8 *)(par->txbuf.buf) = par->startbyte | 0x2;
148 startbyte_size = 1;
149 }
150
151 while (remain) {
152 to_copy = min(tx_array_size, remain);
153 dev_dbg(par->info->device, "to_copy=%zu, remain=%zu\n",
154 to_copy, remain - to_copy);
155
156 for (i = 0; i < to_copy; i++)
> 157 put_unaligned(cpu_to_be16(vmem16[i]), &txbuf16[i]);
158
159 vmem16 = vmem16 + to_copy;
160 ret = par->fbtftops.write(par, par->txbuf.buf,
161 startbyte_size + to_copy * 2);
162 if (ret < 0)
163 return ret;
164 remain -= to_copy;
165 }
166
167 return ret;
168 }
169 EXPORT_SYMBOL(fbtft_write_vmem16_bus8);
170
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] staging: fbtft: fix unaligned vmem writes when txbuf is byte-offset
2026-06-25 11:02 ` [PATCH] staging: fbtft: fix unaligned vmem writes when txbuf is byte-offset suryasaimadhu
2026-06-25 13:20 ` kernel test robot
@ 2026-06-25 13:53 ` kernel test robot
2026-06-25 13:59 ` Andy Shevchenko
2 siblings, 0 replies; 4+ messages in thread
From: kernel test robot @ 2026-06-25 13:53 UTC (permalink / raw)
To: suryasaimadhu, andy
Cc: llvm, oe-kbuild-all, gregkh, dri-devel, linux-fbdev,
linux-staging, linux-kernel, suryasaimadhu
Hi suryasaimadhu,
kernel test robot noticed the following build errors:
[auto build test ERROR on staging/staging-testing]
url: https://github.com/intel-lab-lkp/linux/commits/suryasaimadhu/staging-fbtft-fix-unaligned-vmem-writes-when-txbuf-is-byte-offset/20260625-190423
base: staging/staging-testing
patch link: https://lore.kernel.org/r/20260625110237.304435-1-suryasaimadhu369%40gmail.com
patch subject: [PATCH] staging: fbtft: fix unaligned vmem writes when txbuf is byte-offset
config: hexagon-allmodconfig (https://download.01.org/0day-ci/archive/20260625/202606252144.F56jkpaD-lkp@intel.com/config)
compiler: clang version 23.0.0git (https://github.com/llvm/llvm-project 6cc609bb250b21b47fc7d394b4019101e9983597)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260625/202606252144.F56jkpaD-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202606252144.F56jkpaD-lkp@intel.com/
All errors (new ones prefixed by >>):
>> drivers/staging/fbtft/fbtft-bus.c:157:4: error: call to undeclared function 'put_unaligned'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
157 | put_unaligned(cpu_to_be16(vmem16[i]), &txbuf16[i]);
| ^
1 error generated.
vim +/put_unaligned +157 drivers/staging/fbtft/fbtft-bus.c
113
114 /*****************************************************************************
115 *
116 * int (*write_vmem)(struct fbtft_par *par);
117 *
118 *****************************************************************************/
119
120 /* 16 bit pixel over 8-bit databus */
121 int fbtft_write_vmem16_bus8(struct fbtft_par *par, size_t offset, size_t len)
122 {
123 u16 *vmem16;
124 __be16 *txbuf16 = par->txbuf.buf;
125 size_t remain;
126 size_t to_copy;
127 size_t tx_array_size;
128 int i;
129 int ret = 0;
130 size_t startbyte_size = 0;
131
132 remain = len / 2;
133 vmem16 = (u16 *)(par->info->screen_buffer + offset);
134
135 gpiod_set_value(par->gpio.dc, 1);
136
137 /* non buffered write */
138 if (!par->txbuf.buf)
139 return par->fbtftops.write(par, vmem16, len);
140
141 /* buffered write */
142 tx_array_size = par->txbuf.len / 2;
143
144 if (par->startbyte) {
145 txbuf16 = par->txbuf.buf + 1;
146 tx_array_size -= 2;
147 *(u8 *)(par->txbuf.buf) = par->startbyte | 0x2;
148 startbyte_size = 1;
149 }
150
151 while (remain) {
152 to_copy = min(tx_array_size, remain);
153 dev_dbg(par->info->device, "to_copy=%zu, remain=%zu\n",
154 to_copy, remain - to_copy);
155
156 for (i = 0; i < to_copy; i++)
> 157 put_unaligned(cpu_to_be16(vmem16[i]), &txbuf16[i]);
158
159 vmem16 = vmem16 + to_copy;
160 ret = par->fbtftops.write(par, par->txbuf.buf,
161 startbyte_size + to_copy * 2);
162 if (ret < 0)
163 return ret;
164 remain -= to_copy;
165 }
166
167 return ret;
168 }
169 EXPORT_SYMBOL(fbtft_write_vmem16_bus8);
170
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] staging: fbtft: fix unaligned vmem writes when txbuf is byte-offset
2026-06-25 11:02 ` [PATCH] staging: fbtft: fix unaligned vmem writes when txbuf is byte-offset suryasaimadhu
2026-06-25 13:20 ` kernel test robot
2026-06-25 13:53 ` kernel test robot
@ 2026-06-25 13:59 ` Andy Shevchenko
2 siblings, 0 replies; 4+ messages in thread
From: Andy Shevchenko @ 2026-06-25 13:59 UTC (permalink / raw)
To: suryasaimadhu
Cc: andy, gregkh, dri-devel, linux-fbdev, linux-staging, linux-kernel
On Thu, Jun 25, 2026 at 07:02:37PM +0800, suryasaimadhu wrote:
> fbtft_write_vmem16_bus8() and fb_ra8875's write_vmem16_bus8() offset
> txbuf16 by one byte for a command/start prefix, then store 16-bit pixel
> data via txbuf16[i]. On strict-alignment architectures this can fault
> the same way as the write_reg path fixed in the previous patch.
.write_reg()
Can you provide a real world example of the failure?
> Use put_unaligned() for these stores.
Sounds like a fix without Fixes tag.
> Signed-off-by: suryasaimadhu <suryasaimadhu369@gmail.com>
Use your name in accordance with your official documents.
...
> +++ b/drivers/staging/fbtft/fb_ra8875.c
> @@ -10,6 +10,7 @@
> #include <linux/delay.h>
>
You should move this blank line to be...
> #include <linux/gpio/consumer.h>
> +#include <linux/unaligned.h>
...here.
> #include "fbtft.h"
...
> #define DRVNAME "fb_ra8875"
Are other drivers also being affected?
...
> +++ b/drivers/staging/fbtft/fbtft-bus.c
Also needs linux/unaligned.h.
> + put_unaligned(cpu_to_be16(vmem16[i]), &txbuf16[i]);
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 4+ messages in thread