Hello Paul Kocialkowski,
The patch efeeaefe9be5: "drm: Add support for the LogiCVC display
controller" from May 20, 2022, leads to the following Smatch static
checker warning:
drivers/gpu/drm/logicvc/logicvc_layer.c:320
logicvc_layer_buffer_find_setup()
warn: impossible condition '(hoffset > (((((1))) << (16)) - 1)) =>
(0-u16max > u16max)'
drivers/gpu/drm/logicvc/logicvc_layer.c
258 int logicvc_layer_buffer_find_setup(struct logicvc_drm *logicvc,
259 struct logicvc_layer *layer,
260 struct drm_plane_state *state,
261 struct logicvc_layer_buffer_setup
*setup)
262 {
263 struct drm_device *drm_dev = &logicvc->drm_dev;
264 struct drm_framebuffer *fb = state->fb;
265 /* All the supported formats have a single data plane. */
266 u32 layer_bytespp = fb->format->cpp[0];
267 u32 layer_stride = layer_bytespp * logicvc->config.row_stride;
268 u32 base_offset = layer->config.base_offset * layer_stride;
269 u32 buffer_offset = layer->config.buffer_offset * layer_stride;
270 u8 buffer_sel = 0;
271 u16 voffset = 0;
272 u16 hoffset = 0;
273 phys_addr_t fb_addr;
274 u32 fb_offset;
275 u32 gap;
276
277 if (!logicvc->reserved_mem_base) {
278 drm_err(drm_dev, "No reserved memory base was
registered!\n");
279 return -ENOMEM;
280 }
281
282 fb_addr = drm_fb_cma_get_gem_addr(fb, state, 0);
283 if (fb_addr < logicvc->reserved_mem_base) {
284 drm_err(drm_dev,
285 "Framebuffer memory below reserved memory
base!\n");
286 return -EINVAL;
287 }
288
289 fb_offset = (u32) (fb_addr - logicvc->reserved_mem_base);
290
291 if (fb_offset < base_offset) {
292 drm_err(drm_dev,
293 "Framebuffer offset below layer base
offset!\n");
294 return -EINVAL;
295 }
296
297 gap = fb_offset - base_offset;
298
299 /* Use the possible video buffers selection. */
300 if (gap && buffer_offset) {
301 buffer_sel = gap / buffer_offset;
302 if (buffer_sel > LOGICVC_BUFFER_SEL_MAX)
303 buffer_sel = LOGICVC_BUFFER_SEL_MAX;
304
305 gap -= buffer_sel * buffer_offset;
306 }
307
308 /* Use the vertical offset. */
309 if (gap && layer_stride && logicvc->config.layers_configurable)
{
310 voffset = gap / layer_stride;
311 if (voffset > LOGICVC_LAYER_VOFFSET_MAX)
312 voffset = LOGICVC_LAYER_VOFFSET_MAX;
313
314 gap -= voffset * layer_stride;
315 }
316
317 /* Use the horizontal offset. */
318 if (gap && layer_bytespp &&
logicvc->config.layers_configurable) {
319 hoffset = gap / layer_bytespp;
Can "gap / layer_bytespp" ever be more than USHRT_MAX? Because if so
that won't fit into "hoffset"
--> 320 if (hoffset > LOGICVC_DIMENSIONS_MAX)
321 hoffset = LOGICVC_DIMENSIONS_MAX;
322
323 gap -= hoffset * layer_bytespp;
324 }
325
326 if (gap) {
327 drm_err(drm_dev,
328 "Unable to find layer %d buffer setup for 0x%x
byte gap\n",
329 layer->index, fb_offset - base_offset);
330 return -EINVAL;
331 }
332
333 drm_dbg_kms(drm_dev, "Found layer %d buffer setup for 0x%x byte
gap:\n",
334 layer->index, fb_offset - base_offset);
335
336 drm_dbg_kms(drm_dev, "- buffer_sel = 0x%x chunks of 0x%x
bytes\n",
337 buffer_sel, buffer_offset);
338 drm_dbg_kms(drm_dev, "- voffset = 0x%x chunks of 0x%x bytes\n",
voffset,
339 layer_stride);
340 drm_dbg_kms(drm_dev, "- hoffset = 0x%x chunks of 0x%x bytes\n",
hoffset,
341 layer_bytespp);
342
343 if (setup) {
344 setup->buffer_sel = buffer_sel;
345 setup->voffset = voffset;
346 setup->hoffset = hoffset;
347 }
348
349 return 0;
350 }
regards,
dan carpenter
